Method for treatment of agricultural waste

ABSTRACT

A method for treating a portion of liquid waste manure comprising adding a first reagent to the portion in a first vessel to cause the formation of waste manure flocs of a first size; adding a second reagent to liquid portion to cause growth of the waste manure flocs of the first size into separable waste manure flocs; adding optionally a third reagent to the portion of liquid containing waste manure flocs to cause further growth of the separable waste manure flocs; separating the liquid volume containing separable waste manure flocs into a waste manure sludge and a first filtrate; and dewatering the waste manure sludge in a filtration system comprising a first filter including a first housing, a first displaceable filter medium, and a first displacement actuator disposed between the first housing and the first displaceable filter medium.

This invention relates in one embodiment to a method for treatment ofanimal manure, and more particularly to the treatment of bovine manurein dairy operations in an environmentally acceptable manner.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority from the applicant's U.S. provisionalpatent application Ser. No. 60/891,505 filed Feb. 24, 2007. Thedisclosure of this provisional patent application is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Processes and apparatus for treatment of animal manure in agriculturalapplications.

2. Description of Related Art

The cleanup and handling of dairy cattle, beef cattle, swine, andpoultry manure has become a crucial issue in the management ofwatersheds throughout the United States. There has been increasingpublicity and stricter environmental requirements and enforcementregarding this issue, exemplified by the continuing concern over thebattle to maintain water quality in areas such as the Chesapeake Bay,New York watersheds, and now sections of the Gulf or Mexico. Majorcatastrophic releases of manure as well as perpetual normal operationaldischarges of manure into sensitive watersheds have raised awareness ofthis issue by the general public.

Processes and chemical treatment regimens for the treatment of animalwaste streams are known. For example, U.S. Pat. No. 6,245,121 of Lamy etal., the disclosure of which is incorporated herein by reference,describes a process for the treatment of aqueous effluents containingorganic and inorganic matter and having a solids content of at most 12%by weight to provide a purified liquid phase and a solid organicfertilizer or organic soil improver. The process includes subjecting theeffluent to one or more primary liquid/solid separation steps to obtaina liquid medium containing no more than 3% by weight of dry matter andhaving a turbidity of at most 300 NTU and a collection of concentratescontaining in total 15% by weight dry matter. The liquid medium issubjected to ultra filtration or micro filtration to obtain an ultrafiltrate or a micro filtrate containing at most 1% by weight dry matterand having a turbidity of at most 100 NTU. The ultra filtrate or microfiltrate is subjected to a reverse osmosis operation to obtain aconcentrate and a permeate. The permeate constitutes a purified aqueousphase.

United States Patent Application Publication No. US 2003/0057160 ofWilliams et al., the disclosure of which is incorporated herein byreference, describes an animal waste treatment method comprisingflushing animal waste from a barn to a holding tank where the waste ismixed with an alkaline solution to kill pathogens. After neutralization,the solution is separated into solids and liquids. The liquid is treatedand recycled as flushing water to dean the barns and/or drinking waterfor the animals. The solids are separated into digested and undigestedfeed. The digested feed is further processed for use as a fertilizer andthe undigested feed is processed for use as animal feed.

United States Patent Application Publication No. US 2005/0205496 ofPullman et al., the disclosure of which is incorporated herein byreference, discloses a process for treating liquid waste materialcomprising first adding a chemical flocculent to the liquid wastematerial followed by mixing to promote flocculation. The floc materialis subsequently separated to produce a bulk clarified liquid, with thefloc material being subjected to a solids separation to extract furtherbulk clarified liquid. The collected bulk clarified liquid is thenrecycled back into at least one of the steps of adding a chemicalflocculent and solids separation of the floc material.

Dairy cattle, beef cattle, swine, poultry and other confined animalfeeding operations (CAFO's) require significant capital and operatingcosts for transportation and/or handling, separation and spreading ofmanure. Current technologies for solids and nutrient separation haveinherent limitations, are costly to operate, and result in the use oflarge quantities of fuel and labor in order to provide solid effluentsthat can either be recycled or are environmentally acceptable to spreadon farmlands, and water-based effluents that are either useful inirrigation, in livestock operations, or as potable water, or areenvironmentally acceptable to spread on farmlands.

What is needed is a process for treating animal waste that is low incapital equipment cost, low in waste transportation cost, simple tooperate, and that provides solid and liquid effluents with the aboveattributes.

SUMMARY OF THE INVENTION

To meet this need, the applicant has invented a process to clarify theliquid portions of manure and isolate problematic nutrients, and in somecases render them inert, in dewatered manure solids. Such problematicnutrients have contributed to the contamination of the watershedsmentioned above. The applicant's process cleans such waste streamsbeyond the capability of any existing commercially feasible competingtechnology. The applicant's process further results in energy costreduction for spreading high-solids manure slurries, and isolation ofproblematic nutrients and sediments, which allows flexibility in manuremanagement and spreading.

In accordance with the present invention, there is provided a method andan apparatus for treating a liquid or semi-solid portion of animal wastemanure. The method comprises adding a first reagent to the portion in afirst vessel to cause the formation of waste manure flocs of a firstsize; adding a second reagent to the liquid portion to cause growth ofthe waste manure flocs of the first size into separable waste manureflocs; adding optionally a third reagent to the liquid portion of liquidcontaining waste manure flocs to cause further growth of the separablewaste manure flocs; separating the liquid volume containing separablewaste manure flocs into a waste manure sludge and a first filtrate; anddewatering the waste manure sludge in a filtration system comprising afirst filter including a first housing, a first displaceable filtermedium, and a first displacement actuator disposed between the firsthousing and the first displaceable filter medium.

The first reagent is preferably ferric chloride, and the second reagentpreferably includes a cationic polymer. The third reagent may include ananionic polymer

In one embodiment of the process, bulking agents may be added ifrequired to enhance the formation of the flocs or to enhance thefilterability. This is not always required but the applicant hasdiscovered that there is be a benefit in increasing the final percentageconcentration of dry solids in the dewatered sludge and/or decreasingthe processing time through the use of such agents. These agents includebut are not limited to materials such as reclaimed manure beddingsolids, and the like.

The filtrate may be recycled back into the waste treatment system as adiluent at certain points, or the filtrate may be used in nearby farmingoperations such as washdowns of livestock feed barn floors, orirrigation and/or fertilization of crops. The filtrate may be furtherprocessed with sterilization means such as an ozone sterilizer, andpotentially used as wash down water for milk house or other livestockoperations, and/or foot bath flush water in place of cupric sulfatesolutions and/or in certain instances as potable water for livestock.

The method of the present invention may be performed as a continuousprocess, i.e. wherein the liquid volume being treated flows continuouslythrough a vessel formed as an elongated pipe as the reagents are addedthrough injection ports. Alternatively, the method may be performed as asemi-continuous or batch process in which the volume being treated flowsintermittently from a waste holding vessel to one or more tanks fordilution and reagent addition. Prior to adding flocculants/coagulants tothe liquid waste, the liquid volume of animal waste may be first treatedwith a manure digester. Alternatively or additionally, the liquid volumeof animal waste may undergo a first mechanical separation process,thereby removing large bulk solids by a screw press, a roller press, arotary drum filter, or the like.

The method is also adaptable to animal waste streams comprised ofdifferent types of livestock bedding. The livestock bedding may becomprised of sawdust, straw or other shredded grain plant matter, and/orsand. In the instance in which sand is present in the waste stream, thesystem may include centrifugal sand-manure separator such as ahydrocyclone, and/or other mechanical equipment such as a gravity drivensand-manure separator near the waste stream source, which separates andrecovers the sand for reuse in bedding.

One aspect of the invention is based on the discovery that at certainpoints in the process, the flocs in the liquid volume are shearsensitive, i.e. high liquid shear rates cause the flocs to be brokendown and rendered difficult or impossible to economically separate infiltration equipment. By providing material handling equipment such aspumps and mixers that operate at reduced liquid shear rates, flocs areproduced that are more easily separated from the liquid volume. In theoptimum configuration is has been determined that movement and transferof the flocculated manure by means of gravity is best.

Another aspect of the invention is based on the discovery that the stepsof separating the liquid volume containing final flocs into a sludge anda filtrate, and dewatering the sludge are best performed by an “activefilter” which first retains the solid flocs as a sludge upon a filtermedium that is held in a fixed position while allowing a first portionof the filtrate to pass therethrough; and then forcibly squeezes and/ormanipulates a second portion of the filtrate from the sludge containedtherein by forcibly displacing the filter medium against the sludge in asqueezing or lifting action.

The use of an “active filter” to dewater the sludge is superior to otherdewatering methods and filtration devices for several reasons. Theactive filtration process does not utilize high pressure or moving websto apply the dewatering motive pressure to the sludge to achievedewatering. The active filtration process utilizes displacementactuators operating under a controlled sequence to optimize theseparation of the liquid from the sludge by repeatedly disrupting thesludge mass. The displacement actuators may be hydraulically orpneumatically inflated bladders, or other mechanical means and may bealternately actuated and released in programmed sequences to manipulatethe waste manure sludge and dewater it.

In one embodiment, the liquid containing separable waste manure flocsmay be delivered into the active filter in incremental batches, whereina first batch of waste manure sludge is dewatered by manipulationthereof, then a second batch of waste manure sludge from the addition ofa second batch of liquid containing separable waste manure flocs ispartially dewatered by manipulation thereof, and so forth. As thebatches of waste manure sludge accumulate sequentially in the activefilter, they are dewatered each time they are manipulated by the filtermedium which is displaced by the displacement actuators. When all of thebatches have been delivered to the filter, the manipulation of theentire sludge volume within the filter continues until the sludgeachieves the desired or ultimate level of dewatering.

The repeated disruption and manipulation of the sludge mass results inless blinding of the filtration fabric(s) with the manure sludge. Theactive filtration process may be fully automated and does not requiremanual operation of the equipment such as filter presses. The activefiltration process requires significantly less energy than centrifuges,belt filter presses, vacuum drum filters or other commercially availablesystems. The level of discharged sludge solids concentration is easilyadjustable within the active filtration process as may be required bythe disposal method or end use. This is achieved by modification of theprocess parameters, such as displacement actuator operation, cycle time,etc.

In the preferred embodiment, the method further comprises a phaseseparation step that precedes the active filtration. Phase separation isperformed in a gently agitated bulk tank. In general, under optimizedprocess conditions, separable waste manure flocs float to the upperregion of the tank, while the lower region containing supernatant liquidbecomes less concentrated in solids. The phase separation tank is tappedat the upper region to draw off concentrated separable waste manureflocs for active filtration, and at the lower region to draw off dilutesupernatant liquid for further purification. The filtrate from activefiltration and the supernatant from the phase separation tank areblended together. These liquids are of sufficient clarity to optionallybe further purified in an “ultraclarification unit.” In one preferredembodiment, the ultraclarification unit includes a second active filtercomprised of a housing, a displaceable filter medium, and displacementactuators disposed between the housing and the displaceable filtermedium. The second active filter may have the form of a squeeze towerpress.

In accordance with the present invention, there is also provided anapparatus for treating a liquid containing waste manure. The apparatusis comprised of a first vessel, a filtration system in liquidcommunication with the first vessel, a source of a first reagentmaterial in communication with the first vessel, and a source of asecond reagent material in communication with the first vessel. Thefirst filter includes a first housing, a first displaceable filtermedium, and a first displacement actuator disposed between the firsthousing and the first displaceable filter medium. The first reagentmaterial is reactable with the waste manure to form first waste manureflocs of a first size, and the second reagent material is reactable withthe waste manure flocs of the first size to form separable waste manureflocs of a second size larger than the waste manure flocs of the firstsize.

The first reagent is preferably ferric chloride, and the second reagentincludes a cationic polymer. The apparatus may further comprise a sourceof a third reagent material in communication with the first vessel,wherein the third reagent material is reactable with the waste manureflocs of the second size to form separable waste manure flocs of a thirdsize larger than the separable waste manure flocs of the second size.The third reagent includes a cationic polymer.

The apparatus may be configured to process the liquid containing wastemanure in a continuous mode, in which the first vessel is comprised ofan elongated pipe through which flows the portion of the liquidcontaining waste manure. The elongated pipe includes an injection portin communication with the source of first reagent material.Alternatively, the apparatus may be configured to process the liquidcontaining waste manure in a batch or semi-continuous mode, in which thefirst vessel is a tank for receiving the liquid containing waste manure.The tank is in communication with the sources of first, second, andoptionally third reagent materials.

In order to achieve adequate dewatering of the manure sludge, theapplicant has further invented a method to add and blend controlledamounts of amendment materials to the manure before it enters the firstfilter housing. These amendment materials act to disrupt the nature andstability of the gelatinous mass within the housing and promote porositywithin the sludge mass during the dewatering process. This increasedporosity allows for more effective dewatering of the sludge mass duringthe operation of the sludge disruption mechanisms by the filter. Theinsertion point of the amendment materials may be moved upstream in theprocess prior to the chemical addition points should particulatecontaminants within the particular amendment materials require somelevel of chemical treatment to prevent these contaminants from blindingthe filtration fabric in the housing.

As an alternative to or in addition to the addition of the amendmentmaterials, the applicant has invented a method to direct air into andthrough the bed of the dewatering or composting manure. This air willpromote air drying of the manure solids in addition to the drainagepromoted by the repeated disruption of the manure mass within thehousing by the bladders. In this embodiment, the active filterpreferably includes air flow blocking inserts disposed along the filtermedium and along the side walls of the active filter housing.

The filtration system of the apparatus may further include a secondfilter in fluid communication with the first filter. In one preferredembodiment, the second filter is also an active filter and is comprisedof a housing, a displaceable filter medium, and displacement actuatorsdisposed between the housing and the displaceable filter medium. Thesecond filter may be formed as an elongated cylinder, with thedisplaceable filter medium is formed as an elongated tubular bag. Thehousing of the first filter may be also be formed as an elongatedcylinder with the corresponding filter medium formed as an elongatedtubular bag. In one preferred embodiment, the first filter is formed asbox, with its displaceable filter medium formed as a box-shaped bag.

The apparatus may further include a phase separation tank incommunication with the first vessel and the filtration system. The phaseseparation tank is comprised of a lower region, a middle region, and anupper region, and an inlet port in a middle region of the tank, a firstoutlet port in the upper region of the tank, and a second outlet port ina lower region of the tank. A mixer is preferably disposed in the phaseseparation tank, and includes an upper impeller, a middle impeller, anda lower impeller. The apparatus may further include a hydrocyclone forremoving sand from the liquid waste manure.

The apparatus may include an improved active filter. The active filteris comprised of a box-shaped housing comprised of a bottom wall, twoopposed side walls, an end wall, and a door opposite the end wall; afirst filter medium formed as a box-shaped bag and including a bottompanel, opposed first and second side panels disposed along the twoopposed side walls, and a third panel disposed along the end wall; asecond filter medium disposed along the door opposite the end wall; anda first displacement actuator disposed between the bottom wall of thebox-shaped housing and the bottom panel of the first filter medium. Theopposed first and second side panels are of a sufficient length toextend around the vertical ends of the opposed first and second sidewalls of the housing to the outer surface of the housing, to which theymay be secured with suitable fastening means. Similarly the bottom panelis of sufficient length to form a flap extending over the horizontal endof the bottom wall where it may be secured with a suitable fasteningmeans or allowed to hang down past the horizontal end of the bottomwall. When the door of the filter housing is closed, the flap isdisposed between the bottom edge of the door and the horizontal end ofthe bottom wall.

As a result of the methods and apparatus of the invention, animal wastefrom an agricultural operation such as a dairy, cattle, poultry, swine,or other livestock farm can be treated in an economical andenvironmentally beneficial manner. The environmental benefits areprovided through improved filtrate clarity, and control andsequestration of problematic nutrients and sediments, among otherfactors.

An additional benefit of the invention is the ability to dewater andprovide liquid manure as a solid or semi solid mass to anaerobicdigestion processes. This has two particular benefits. In the instanceof on-farm digester installations the ability to thicken the liquidmanure prior to its introduction into the digester may allow for morecost effective digester design based upon a lower liquid volume. In theinstance of remote community-type digester installations the ability tothicken the manure prior to its transfer to the community digester hasthe direct impact of lowering transportation costs as well as thepotential benefit mentioned above of reduction in the capital cost.Furthermore, in order to accommodate the control of transportation coststhe manure supply for community digesters may be dewatered withconventional mechanical means at the remote farm sites and only thedewatered solids transferred to the community digester. The fines in thefiltrate from the conventional dewatering equipment represent at least50% of the digestible organic matter in the anaerobic digester. Thesefines would be left at the remote farm site. The applicant's processwould provide for the capture, dewatering and cost effectivetransportation of these solids to the community digester.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by reference to the following drawings,in which like numerals refer to like elements, and in which:

FIG. 1 is a general flowchart depicting steps of the animal wastetreatment method of the present invention;

FIG. 2 is a schematic diagram of one embodiment of an animal wastetreatment apparatus of the present invention;

FIG. 3 is a schematic diagram of another embodiment of an animal wastetreatment apparatus of the invention wherein the animal waste mayinclude sand;

FIG. 4 is a cross-sectional schematic illustration of a phase separationtank used in the present invention;

FIG. 5 is a schematic cross-sectional illustration of a “box” typefilter that may be used in the present invention;

FIG. 6 is a schematic illustration of one embodiment of the applicant'swaste treatment apparatus including simple instrumentation and controlloops;

FIG. 7A is a schematic cross-sectional illustration of a “box” typefilter including means for producing compost from the sludge collectedtherein;

FIG. 7B is a detailed cross-sectional illustration of a sidewall regionof the “box” type filter of FIG. 7A showing an air flow blocking insertdisposed between the filter medium and the sludge collected therein;

FIG. 8A is a schematic cross-sectional illustration of a “box” typefilter with improved filter media;

FIG. 8B is a detailed cross-section of the juncture of a side wall and aside door of the box filter of FIG. 8A, the detail showing the cornerportion of the filter taken along the line 8B-8B in FIG. 8A; and

FIG. 8C is a view of a means for fastening the filter medium to the sidewall of the filter, the detail showing the fastening means within theellipse marked “8C” in FIG. 8B.

The present invention will be described in connection with certainpreferred embodiments; however, it will be understood that there is nointent to limit the invention to the embodiments described. On thecontrary, the intent is to cover all alternatives, modifications, andequivalents as may be included within the spirit and scope of theinvention as defined by the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For a general understanding of the present invention, reference is madeto the drawings. In the drawings, like reference numerals have been usedthroughout to designate identical elements. In describing the presentinvention, a variety of terms are used in the description. Standardterminology is widely used in animal waste treatment art.

In this specification, the terms “animal waste,” “manure waste,” “manureslurry,” and “manure solution” are used interchangeably, and are meantto indicate any liquid, solid, or semi-solid waste matter which containsanimal manure. The waste matter to be treated typically includes bothliquid and solid phases, wherein the solids phase material is comprisedof digested and undigested solid particles of animal feed (hay, grasses,grains, etc.) having a range of sizes. From a rheological standpoint,the bulk waste matter may behave generally as a liquid, i.e. it easilydeforms irreversibly under a small amount of shear. The waste matter maybehave as a semi-solid, having a yield point and requiring a substantialamount of shear force to be exerted before flow results. The wastematter may behave more like a solid, requiring solid conveying equipmentinstead of liquid pumping equipment to deliver it to the applicant'swaste treatment system.

Animal waste may also include urine, and animal bedding matter such assand, sawdust, paper mill sludge, and whole or shredded plant stems,stalks, leaves, cobs, husks, recycled manure and the like. Theapplicant's method and treatment system are capable of treating avariety of manure wastes, including but not limited to bovine, swine,ovine, equine, caprine, bubaline, poultry, and aquatic (e.g. fish farm)manures.

In the applicant's method, referred to commercially as the Nutrient TrapProcess, or “NTP”, manure waste may be delivered to the process at anyconcentration or from any source, including raw manure from livestockpens or cages, raw manure “filtrate” from a manure separator, digestedmanure, and/or digester manure “filtrate” from a manure separator. Themanure separator may be any manure separation equipment. The manurewaste may include any form of livestock bedding as recited above. Theapplicant's method has been developed particularly through testing ondairy cattle manure and to a lesser degree swine manure, but theapplicant believes that his method will provide similar satisfactoryperformance on any animal manure including but not limited to thoserecited above. Thus the treatment of any such manures is to beconsidered within the scope of the present invention. With respect tolivestock farming operations in general, slurries of hog manure andchicken manure are the most prevalent additional sources of manure.

In operation of the applicant's method, the incoming manure slurry isdiluted if necessary to a concentration range appropriate for theparticular type of manure waste. This dilution stage enhances thechemical performance of the coagulant and flocculants, but the degree ofenhancement is subject to the nature of the particular manure. Ingeneral, optimum performance of the coagulation and flocculation stepsis typically achieved when the incoming manure slurry between about 1.5and about 2.5 weight percent solids. When the applicant's wastetreatment system is configured to run as a continuous process, theconcentration of the manure slurry may be controlled by dilution withwater, which is preferably recycled filtrate previously discharged fromthe filtration equipment of the system. The concentration of the manuremay be measured by a nuclear absorption concentration monitor or anyother similar device. For applications that contain significant upstreamstorage of animal waste to be treated, which would provide greateruniformity in the influent stream to the process, this control may bemanually set.

The preferred filtration equipment utilized in the applicant's process,and the manner in which it is operated is a significant aspect of thepresent invention. The general operating principles of this “activefiltration” equipment are described and shown in U.S. Pat. No. 5,614,092of DiLeo, the disclosure of which is incorporated herein by reference.In the applicant's chemical treatment of the manure waste, the manure ischemically modified with a comparatively low cost formulation. Themanure is subsequently handled in a manner that minimizes shear on thetreated manure waste, such that the manure flocs are not broken up andredispersed. Subsequently, in the active filtration equipment, durablepneumatic or hydraulic bladders are inflated and deflated to manipulatethe manure within the filter in a manner that accelerates manuredewatering through the filter medium. Alternately, mechanically actuateddevices may be utilized to manipulate the filter medium and the manureas well.

The effluent water discharged from the applicant's process has very lowsuspended solids concentration, contains essentially no dissolvedphosphates, and has greatly reduced levels of organic nitrogen. Theseresults are obtained at chemical loading rates at or below conventionalchemical flocculation technologies utilized in other manure wastetreatment processes.

In one exemplary embodiment to be further described herein, the nutrientremoval rates from the liquid manure waste consistently demonstrated bythe process were as follows:

-   -   Phosphorous: ˜97.5-99%++removal    -   Organic Nitrogen: 85% to 99% removal    -   Fecal Matter: 99% removal    -   Total Manure Solids: 94 to 97% removal    -   Suspended Manure Solids: Solids removed down to a particle size        range of 20-50 microns; With optimum chemical treatment and        associated reaction time all visually detectable solids are        removed.        The resultant dewatered manure solids contain the captured        manure nutrients. Without intending to be bound by any        particular theory, the applicant believes that through the        reaction of the ferric chloride and the phosphorous compounds in        the manure slurry, ferric phosphate is produced, which is an        insoluble, inert material. This ferric phosphate is captured        within the filter with the dewatering manure solids. Therefore        the phosphate in the dewatered solids has been rendered        insoluble by the applicant's process, making it no longer        available to compromise the downstream watershed. Through the        chemical analysis for the manure influent to the process, the        filtrate, and the dewatered solids, it is consistently observed        that the phosphorous materials are substantially removed from        the filtrate and remain with the dewatered solids. The organic        nitrogen in the dewatered solids has been bound chemically into        less soluble or insoluble forms that significantly retard their        re-entry into the downstream watershed through decomposition.        The chemistry of these reactions is not specifically defined due        to the variety of organic nitrogen compounds. However, through        the chemical analysis for the manure influent to the process,        the filtrate, and the dewatered solids, it is also consistently        observed that the organic nitrogen materials are substantially        removed from the filtrate and remain with the dewatered solids.        The dewatered solids are readily handled with common dry manure        handling equipment, such as that used to spread the dry manure        as a fertilizer on farm soils.

By capturing the nutrients in the manure in the dewatered solids,instead of having them dissolved in the aqueous liquid phase, twobeneficial results are attained. The nutrients are not available in theliquid to cause adverse effects, such as algae blooms in the downstreamwatershed into which the filtrate may be discharged; and the capturednutrients in the dewatered solids make the solid a good soil fertilizerthat slowly releases the nitrogen nutrients over time.

FIG. 1 is a general flowchart depicting steps of the applicant's manurewaste treatment method. Referring to FIG. 1, method 5 comprises step 10,delivering a liquid containing waste manure to the treatment apparatus;step 20, adding a first reagent to the volume to produce a liquid volumecontaining waste manure flocs of a first size, and referred to herein asmicroflocs; step 30, adding a second reagent to the liquid volumecontaining microflocs to cause growth of the waste microflocs intoseparable waste manure flocs of a second size (further referred toherein as primary flocs); optional step 40, adding a third reagent tothe liquid volume containing the separable flocs to cause further growthof the separable waste manure flocs, thereby producing a liquid volumecontaining secondary or “final” flocs; optional step 45, performing aphase separation of a portion of the flocculated solids from the bulkliquid; step 50, separating the liquid volume containing primary orfinal flocs into a sludge and a filtrate; and step 60, dewatering thesludge.

The filtrate may be placed in temporary storage in a holding vessel instep 80. From that point, the filtrate may be recycled back into thewaste treatment apparatus as a diluent at certain points as indicated byline 82; or the filtrate may be used in step 90 in other farm operations84 such as washdowns of livestock feed barn floors, or irrigation ofcrops; or the filtrate may be further processed in step 85 withsterilization means such as an ozone sterilizer, and potentially used aspotable water for livestock, wash down water for milk house operationsor foot bath flush water in place of cupric sulfate solutions.

The method 5 may be performed as a continuous process, i.e. the liquidvolume being treated flows continuously through an elongated pipe and/orvessels as the reagents are added. In the simplest form, the elongatedpipe is the reaction vessel in which the flocs of waste manure areproduced. Alternatively, the method may be performed as asemi-continuous or batch process in which the volume being treated flowsintermittently from a waste holding vessel to one or more vessels fordilution and reagent addition. Portions of the process, or the entireprocess may be embodied as a portable system, or a stationary system.The method 5 may further include the manure digestion and/or mechanicalseparation steps as will be described with reference to FIGS. 2 and 3.

Additionally, it is noted that although the apparatus 100 and 101 ofFIGS. 2 and 3 are depicted as including pumps at various locations toeffect the transfer of liquids at various points, other suitable meansor accommodations may be provided to accomplish the liquid transfers.For example, the apparatus could be arranged such that gravity feed isperformed from various upstream points in the apparatus to downstreampoints. Alternatively or additionally, certain vessels could be sealedand pressurized to enable such transfers.

One preferred filter for performing step 50 of separating the liquidvolume containing primary or final flocs into a sludge and a filtrate,and step 60 of dewatering the sludge, is a filter that forcibly squeezesand/or manipulates the sludge contained therein, thereby dewatering thesludge into a sufficiently dry mass to be suitable for use as compostand/or spreading as a soil fertilizer. In one embodiment that includesstep 65, the filtrate is sufficiently purified by use of a polishingfilter to enable discharge thereof to other farming operations requiringhigher purity, should the primary filtration equipment not providesufficient clarity.

FIG. 2 is a schematic diagram of one embodiment of a manure wastetreatment apparatus that may be used to perform the manure wastetreatment method 5. Liquid waste manure may be delivered to apparatus100 at a range of different concentrations. The apparatus 100 and method5 of the present invention are capable of treating liquid waste manurecontaining from between about 1% to at least about 12% weight percentsolids.

To perform step 10 of method 5 shown in FIG. 1, liquid waste manure isdelivered to apparatus 100 from a manure source. Manure source 102 maybe one or more barns, feedlots, milking parlors, silage bunkers etc.,from which manure waste is provided directly to apparatus 100.Alternatively, manure source 102 may be a manure storage vessel such asa manure lagoon or tank, or manure source 102 may be a tank truck orother transporter by which manure waste is delivered to apparatus 100.The waste manure may be diluted prior to delivery to apparatus 100 byeither fresh water, or more preferably by recovered filtrate stored ingray water tank 170 or lagoon 175. The concentration of the waste manureslurry delivered to apparatus 100 may be measured by a nuclearabsorption or microwave concentration monitor, or an ultrasonic flow andconcentration monitor or any other similar device. One example of such asolids concentration monitoring device is a Markland 502 IL suspendedsolids concentration meter produced by Markland Specialty Engineering,Ltd of Ontario Canada.

Prior to the treatment of the manure waste with the chemical reagents A,B, and optionally C, one or more operations (indicated in dotted lineformat) may be performed on the manure waste. The manure waste may beprocessed in a manure digester 104 to obtain a biogas fuel such asmethane from the manure. Alternatively or additionally, the manure maybe processed with a mechanical separator 106 such as a screw press, aroller press, a rotary drum filter, or the like to remove large bulksolids. The solids recovered from mechanical separator 106 may be usefulas recycled bedding 108 for livestock, compost or other beneficial use.The manure digestion step may be integrated downstream in the process,i.e. as digestion of the flocculated and/or filtered manure solids, asopposed to upstream, i.e. prior to the flocculation steps.

Apparatus 100 may be configured as a batch or semi-continuous process,and in such case will include mixing tank 110. A batch of manure wasteis delivered from manure source 102, or from manure digester 104 and/ormechanical separator 106. As indicated previously, dilution water may beadded to dilute the liquid manure waste to a required concentrationrange appropriate for the treatment. The dilution is performed in orderto enhance the chemical performance of the reagents and to simplifydownstream control. The degree of enhancement is dependent upon theparticular manure waste material, which may vary in its specificchemical nature (particularly by animal species, bedding material andanimal diet). Selection of the optimum concentration may be achievedthrough experimental observations of the response of the reagents atvarying concentrations.

In order to perform step 20 of method 5, apparatus 100 is provided witha source 120 of reagent A for producing small coagulated pin flocs ormicroflocs in mix tank 110. As used herein, the terms “microfloc” and“pin floc” are used interchangeably and are meant to indicateprecipitated solid phase particles having a characteristic dimension onthe order of 20 to 100 microns. Stated alternatively, the size of themicroflocs is at about the threshold of what is just barely visible to atypical human with 20-20 vision.

In the preferred embodiment, reagent A is ferric chloride althoughalternatively, alum (typically referred to as aluminum sulfate, withoutthe precursor), polyaluminum chloride (PAC) or similar metal halideinorganic salt solutions may also be suitable. However, the use of theferric chloride (FeCl₃) as a constituent in the manure is the mostpreferable and currently the most cost effective reagent. In addition,the iron byproducts of the process are considered more acceptable forintegration into the soil than aluminum byproducts by the agriculturalcommunity, and in light of various environmental regulations. Theeffective amount of ferric chloride to be added to tank 110 (or pipeline112 in continuous mode operation) varies based upon the nature of theparticular manure to be treated. Optimum performance has been typicallyachieved between about 0.25 to 1.5 weight percent ferric chloride withrespect to the total weight of the contents of tank 110 or the weight ofa unit volume passing through the pipeline 112, depending upon theconcentration and nature of the manure.

The ferric chloride may be provided as a liquid solution from source 120via pump 122 to mixing vessel 110. Source 120 may be a holding vessel inwhich the solution is prepared, or source 120 may be a pre-packageddisposable container of solution that is connectable to pump 122. Theconcentration of the ferric chloride reagent contained in source 120 isbetween about 30 to about 45 weight percent solids. Source 120 may beplaced upon a rack 121, which may be elevated above tank 110, such thatthe ferric chloride reagent can be gravity fed into tank 110. Source 130of reagent B and source 140 of reagent C may also be located proximateto source 120 on rack 121.

Control of the ferric chloride addition, once the optimum level isdetermined, may be achieved by determining the pH of the slurry (i.e.the pH of the aqueous liquid phase of the slurry) at the optimum solidsconcentration and the optimum ferric chloride concentration. Providedthe solids concentration is reasonably consistent for a given material,the optimum level of ferric chloride will be satisfied at the same pHlevel. The optimum pH for manure varies based upon the nature of theparticular manure. Optimum performance has been typically achievedbetween a pH of about 6.2 to 6.9, depending upon the concentration ofthe manure and the nature of the manure. In most cases the manuredelivered to the process will have a pH in the range of 6.5 to 7.2. Insome instances the pH may be higher. In such cases, it may beeconomically advantageous to utilize a low cost acid or similar reagentto lower the pH to the range of the typical manure prior to the ferricchloride addition, or to blend the acidic reagent with the ferricchloride prior to its addition to tank 110.

In using apparatus 100 to treat manure, the addition of the ferricchloride may be done in a batch mode in vessel 130, or in a continuousmode by injection into the flowing waste manure slurry as it is pumpedthrough pipeline 112. In one preferred embodiment, the ferric chlorideis injected into the pipeline 112 downstream of the transfer pump 105,which pumps the manure slurry from the manure source 102 to theseparation tank 150. The pipeline 112 may be provided with a motionlessmixer or other mixing means therein to achieve rapid mixing of theferric chloride with the manure slurry.

Thus in a continuous process, the mixing tank 110 is replaced with anelongated pipe 112, an injection port for addition of the ferricchloride to the flowing manure slurry, and mixing means in the pipe ifnecessary. A pH probe may also be provided in the pipe for use incontrol of the addition of the ferric chloride to the manure.Utilization of pH control provides consistent continuous processing ofthe slurry. For applications that contain significant upstream storage,which would provide for uniformity in the influent stream to theprocess, this control may be manually set.

The addition of the ferric chloride to the manure as described hereinresults in the formation of microflocs or pin flocs. The applicant hasobserved that the pin floc produced by the addition of reagent A isapparently resistant to mechanical disruption due to shear, providedthat extreme shear is not imparted for extended periods. Although theapplicant has not quantified the upper limit of acceptable shear energybeyond which breakdown of the pin floc will occur, is considered optimumto avoid the use of high shear material handling devices such ascentrifugal pumps and mixers having high impeller speeds in this phaseof the process.

At this initial step of converting the liquid manure waste into aseparable solid phase, the pin floc is not filterable in a costeffective manner, nor will a solid collected in a filtration device bein a form that is easily dewatered and handled, rendering it suitablefor compost or soil fertilizer. Further treatment steps are highlypreferred to obtain such a solid. Step 30 of method 5, the addition of aprimary floc forming reagent is performed next.

It is also noted that the flocculation process may proceed without theaddition of ferric chloride. Processes are known for the treatment ofanimal manures with polyacrylamides alone. However, the applicant hasobserved that the addition of the ferric chloride, or other similarcoagulating agent, enhances the performance of the polyacrylamidecationic polymers by reducing the chemical loading requirements andimproving the clarity of the filtrate and the resultant removal ofadditional particulate matter from the filtrate.

In order to perform step 30 of method 5, apparatus 100 is provided witha source 130 of reagent B for producing primary flocs of manure waste inpipeline 112. The addition of reagent B to the microfloc containingliquid as described herein results in the formation of “primary floc,”i.e. floc of a second, larger size that is cost-effectively separablefrom the liquid. Although the microfloc may be considered separable,given a filter medium having sufficiently small pores, and sufficienttime to perform the filtration, such a filtration is usually notcost-effective or desirable as compared to the use of a reagent B toproduce the primary floc. As used herein, the term “primary floc” ismeant to indicate solid phase particles that have a size larger thanmicroflocs, having a characteristic appearance of dark, small to mediumcurd cottage cheese in a dilute water slurry, and a typicallycharacteristic but not required dimension of between about 0.25 inchesand about 0.75 inches.

In the preferred embodiment, reagent B is a cationic polymer. Morepreferably, reagent B is a high molecular weight high charge cationicpolymer, such as a linear cationic polyacrylamide. Even more preferably,reagent B is a water and oil emulsion of a cationic polyacrylamideincluding appropriate surfactants to stabilize the emulsion. One exampleof a suitable water and oil emulsion of a cationic polyacrylamide isDrewfloc 2425 manufactured and sold by the Drew Industrial Division ofthe Ashland Corporation of Boonton, N.J. Other suitable cationicpolymers and water and oil emulsions thereof will be apparent to thoseskilled in the art.

The cationic polymer, being water dispersible, or being the preferredwater and oil emulsion is provided as a liquid from source 130 via pump132. Source 130 may be a holding vessel in which the cationic polymerliquid is prepared, or source 130 may be a pre-packaged disposablecontainer of solution/emulsion that is connectable to pump 132. As usedherein, the term “solution” when used in regard to mixtures of cationicor anionic polymers in water is meant to indicate liquids which maycontain both dissolved polymer, suspended fine particles of polymer inthe liquid, and/or emulsified droplets containing cationic polymer in awater and oil emulsion.

The addition of the cationic polymer may be done in batch mode in mixingtank 110, or in a second vessel (not shown) immediately downstream frommixing tank 110. Alternatively, addition of the cationic polymer may bedone in continuous mode by injection of the cationic polymer into theslurry as it is pumped through pipeline 112. In one preferredembodiment, the cationic polymer is injected into the pipeline 112downstream of the transfer pump 105, but at least ten seconds (withrespect to average residence time in pipeline 112) downstream of theferric chloride injection. This distance and time delay allows foradequate reaction of the ferric chloride with the manure to form the pinfloc prior to the addition of the cationic polymer. The optimum locationof the cationic polymer injection is just prior, approximately 1 to 5seconds prior to the entrance of the manure slurry into the separationtank 150 or the active filter 160, provided there is a mechanism formixing of the polymer within the pipeline such as a motionless mixer.This location minimizes the amount of shear forces the floc is subjectedto within the pipeline but does allow for mixing of the polymer with themanure in the pipeline prior to it entering the separation tank 150 orfilter 160.

To prepare the cationic polymer of reagent B, the polymer is initiallydispersed and/or dissolved into solution with fresh water and orfiltrate from the end of the process, which is stored in gray water tank170 or alternately in a lagoon 175. This initial solution is optimallyin the range of about 0.25 to 0.5 weight percent solid polymer. Thefiltrate from the end of the process is sufficiently clean to allow forits use as the water source for the cationic polymer solution in thisstep of the process. Subsequent to initial solution preparation, thepolymer may be further diluted by addition directly to the reagent Breservoir, or by addition to the pipeline 134 near pump 132.

Crystalline forms of the cationic polymers are commercially available,which are dispersible in water and have been utilized in the applicant'sprocess. However, their use has proven difficult and deleterious to theconsistent and proper operation of the process. The uniform and reliabledispersion of the crystalline material into aqueous solutions at farmscale is problematic and is subject to inconsistency due to human error,environmental factors and equipment failures. This had led toinstability in the process, instability of the flocs through the processand inadequate performance of the separation equipment, inconsistentfiltration performance and filtrate clarity, etc. The crystalline formsof the cationic polymer are more expensive than the liquid forms, as isthe equipment for its fully automated and/or manual dispersion, storageand handling.

The prepared reagent B solution is injected into the flowing manurestream in pipeline 112 at a highly diluted concentration. The injectionof this dilution water with the cationic polymer provides forsignificant dilution of the manure at the point of injection of thepolymer. It has been determined that this high dilution considerablyenhances the efficacy of the cationic polymer in forming flocs that areamenable to filtration, particularly with the preferred activefiltration equipment 160 of apparatus 100. Without wishing to be boundto any particular theory, the applicant believes that the dilutedcondition of the flocculated manure stream appears to be produce lessshear forces on the flocs as they pass through the system. This dilutionis typically performed to less than 0.1 weight percent solids. Theactual degree of dilution is dependent upon the nature of the manure.For manure streams that are highly diluted such as from flush systems itmay not be necessary to perform this dilution, as the manure supply willbe sufficiently dilute to achieve the desired performance of thecationic polymer flocculent.

Following the injection of the polymer, a minimal period of time must beallowed for the polymer to react and flocs to form and existingmicroflocs to grow. This may be achieved in line in the transfer pipe112 to the dewatering/filtration equipment 160 or in separation tank150. The pipe 112 may be provided with a low-shear motionless mixer orother mixing means therein (not shown) to achieve rapid mixing of thecationic polymer with the manure slurry. In order to provide an extendedresidence time in pipe 112, the distal end thereof immediately upstreamfrom tank 150 or filtration equipment 160 may be formed as a coil orserpentine-shaped conduit (not shown).

The primary floc prepared as described herein has been found to be shearsensitive. It is necessary to minimize the exposure of this floc toshear forces found in conventional centrifugal and diaphragm pumps andhigh speed agitators. Progressive cavity and/or positive displacementpumps or any pump that imparts minimum shear forces into the slurryprovide the optimum performance, as compared to high shear pumps, suchas centrifugal pumps. The optimum process design includes no exposure ofthe floc-containing slurry to pumping devices following the introductionof the flocculent reagents A and B. Low speed flocculation mixers areoptimum for development of the floc at this stage of the process. Theeffective amount of cationic polymer for producing filtration flocs inthe pipeline 112 or in mixing tank 110 if operating in batch mode variesbased upon the nature of the particular manure. Optimum performance hasbeen typically achieved between about 0.25 to 0.5 weight percentcationic polymer with respect to the weight of a unit volume in pipeline112 or the total weight of the contents of tank 110, but is dependentupon the concentration of the manure and the nature of the manure.

At this step of converting the manure waste into a separable solidphase, the primary floc may still not be optimally filterable in a costeffective manner. In such cases an additional treatment step ispreferred to obtain such a solid. Step 40 of method 5, the addition of asecondary or “large” or “final” floc forming reagent, which increasesthe floc size and/or mechanical stability may be performed next.

In order to perform step 40 of method 5, apparatus 100 is provided witha source 140 of reagent C for producing the secondary flocs of manurewaste solids in mixing tank 110, or pipeline 112 and/or phase separationtank 150. In the preferred embodiment, reagent C is an anionic polymer,and more preferably, a high molecular weight high charge anionicpolymer, such as a linear anionic polyacrylamide. One example of asuitable material comprised of an anionic polyacrylamide is Drewfloc2270 manufactured and sold by the Drew Industrial Division of theAshland Corporation of Boonton, N.J. Other suitable anionic polymerswill be apparent to those skilled in the art.

The anionic polymer, being water soluble, is provided as a liquidsolution from source 140 via pump 142 and conduit 144 to processingvessel 150. Source 140 may be a holding vessel in which the anionicpolymer solution is prepared, or source 140 may be a pre-packageddisposable container of solution that is connectable to pump 142.

The addition of the additional reagent C polymer may be done in batchmode in mixing tank 110, or in a second vessel (not shown) immediatelydownstream from mixing tank 110. Alternatively, addition of the anionicpolymer may be done in continuous mode by injection of the anionicpolymer into the manure slurry as it is pumped through pipe line 112.The pipe 112 may be provided with a low-shear motionless mixer or othermixing means (not shown) therein to achieve rapid mixing of the anionicpolymer with waste manure liquid. In many instances, the cost of thisadditional polymer is not considered economically justified based uponthe satisfactory performance of the apparatus 100 in treating the wastemanure with the pin floc forming reagent A and the primary floc formingreagent B.

This large secondary floc is also shear sensitive. It is necessary tominimize the exposure of this floc to shear forces found in conventionalcentrifugal and diaphragm pumps and high speed agitators. Progressivecavity and or positive displacement pumps or any pump that impartsminimum shear forces into the slurry provide the optimum performance. Asmentioned previously, the optimum process excludes a pump followingintroduction of the reagent C flocculent. Low speed flocculation mixersare optimum for development of the floc at this stage of the process.The effective amount of the anionic polymer for producing larger flocsin the pipeline 112 or a mixing tank if operating in batch mode variesbased upon the nature of the particular manure. Optimum performance hasbeen typically achieved between about 0.05 to 0.15 weight percentanionic polymer with respect to the weight of a unit volume flowing inthe pipeline 112 or the total weight of the contents of the mixing tank,but is also dependent upon the concentration of the manure and thenature of the manure.

The addition of the anionic polymer to the filtration floc-containingliquid as described herein results in the formation of “secondary” or“large” floc. As used herein, the terms “secondary” or “large” floc ismeant to indicate solid phase particles that have a third size at leastequal and usually greater than primary floc, having a characteristicappearance of dark, medium to large curd cottage cheese in a dilutewater slurry, and a typically characteristic but not required dimensionof between about 0.25 inches and about 0.75 inches.

The filtration and/or large floc of manure solids contained in tanks 110and/or 150 that are produced by the method and apparatus of the presentinvention are filterable in a cost effective manner, and can becollected in a filtration device in a form that is easily dewatered andhandled, rendering the solids suitable for use as compost and/orspreading as a solid soil fertilizer. This is because the sequence ofaddition of ferric chloride, then cationic polymer and optionallyanionic polymer provides for a floc of sufficient stability to beeffectively dewatered in an active filtration separation device and toprovide a clear or nearly clear filtrate. The dewatered solids are alsoof a consistency that is readily discharged from the active filtrationdevice and handled by conventional equipment such as a slinger spreader.

In an alternative embodiment, a single polymer agent such as Drewfloc490, a quaternary ammonium cationic polymer which functions as acoagulant and as a mild flocculent, may be utilized for floc formationinstead of the cationic polymer reagent B and the anionic polymerreagent C. However, the floc resulting from the chemical treatmentregimen with ferric chloride plus cationic polymer provided in a liquidform, and in particular, a water and oil emulsion with appropriatesurfactants has proven to be more amenable to active filtration.

The chemical treatment steps 10, 20, 30, and 40 of the applicant'smanure waste treatment method 5 have been described with reference toFIG. 2, which depicts an apparatus 100 for manure waste treatment. Asdescribed previously, apparatus 100 is configured to process manurewaste which contains sawdust or other cellulosic livestock beddingmaterial. In some dairy and other livestock farming operations, sand isused as a bedding material. In order to process manure waste containingsand, an alternative embodiment of the applicant's manure wastetreatment apparatus is provided as depicted in FIG. 3.

Referring to FIG. 3, apparatus 101 is comprised of a manure source 102as described previously. Apparatus 101 further comprises sand recoverysedimentation and conveying equipment 103 and hydrocyclone 107 whichseparates the fine remaining sand from the manure slurry. In oneembodiment, sand recovery equipment is comprised of a separation augeror similar conveyor and followed by a hydrocyclone. The hydrocyclone 107may be as manufactured by the McLanahan Corporation of Hollidaysburg,Pa. This is standard commercially available equipment from many sources.From the point immediately downstream of hydrocyclone 107, apparatus 101functions substantially the same as previously described herein forapparatus 100 of FIG. 2.

It is significant to note that the utilization of the applicant'sprocess and apparatus may render the operation of the hydrocyclone,which is found essential to many sand manure recovery operations,unnecessary; or less such equipment may be required. The hydrocyclone isutilized in current practice to capture minor portions of entrained sandparticulate in the effluent stream from the coarse separation equipment.Its purpose is to improve material recovery for minor incremental costssavings and for mitigation of abrasion and other inherent damage todownstream manure handling equipment. The applicant's process would notprovide for the material recovery. However, the box filter is notsusceptible to damage resulting from the presence of sand in the manureslurry. Furthermore, the applicant's process provides a filtrateessentially free of sand contamination allowing for more effective andflexible reuse of the filtrate within the agricultural operation.

Step 45 of method 5, phase separation of the floc from the manure may beoptionally performed next, prior to filtration of the waste manure flocfrom the liquid. FIG. 4 is a cross-sectional schematic illustration of aPhase Separation Tank (PST) used to perform phase separation 45.Referring to FIGS. 2 and 4, the PST 150 may be employed in severalembodiments of the process. In the preferred embodiment, the PST 150 isdisposed in the apparatus 100 just upstream from the active filter 160.The diluted and chemically treated manure slurry from pipeline 112enters the tank 150 at a mid point inlet 152 approximately within themiddle third of the height of the tank. As the slurry enters the tankthe flocculated manure 151 will tend to rise to the top region 154 ofthe tank 150 and float on top of the supernatant liquid 155. Thesupernatant liquid 155, with adequate residence time, will liberateessentially all of the flocculated solids 151 and be very low insuspended solids, potentially as low as the filtrate from the activefilter. The thickened manure solids 157 near or on top of thesupernatant liquid 155 flow out of the upper outlet nozzle of the PSTand are delivered to the active filter 160. The agitator 159 within thetank 150 serves to keep the slurry moving within the tank and to preventthe formation of large gelatinous masses that cannot exit the upperoutlet 153. In the preferred embodiment, the outlet pipe at nozzle 153and the transfer pipe to the filter housing should be of sufficientdiameter to prevent plugging and to limit hydraulic disruption of theflocculated material. It has been observed that for the phase separationtank as provided for within the embodiment above this diameter should bein excess of four inches in diameter and six inches in diameter issuperior. This diameter is also important in regard to the ability toadd and blend the composting and or dewatering amendment materials tothe manure en route to the filter housing. As used herein, the term“hydraulic disruption” when used in regard to flocculated material in aliquid is meant to indicate disruption of the flocculated material byshear forces in the liquid, such that the size of the flocs is reduced.

The supernatant liquid is drawn off of the bottom of the tank 150through lower outlet 156 using throttling valve 158 to control the flowrate. This rate is set such that the thickened flocculated solids at thetop of the tank flow continuously out of the upper outlet 153 at aconstant rate, with only minor fluctuations in the tank level. Ingeneral, at steady-state operation, the rate of inflow through inlet 152is equal to the sum of the rates of outflow through upper outlet 153 andlower outlet 156.

The supernatant liquid 155 that exits tank 150 through lower outlet 156may drained and/or pumped to the gray water tank 170 or to a lagoon 175.The applicant has observed that the supernatant liquid 155 is often asclear as the filtrate from active filter 160 so it is combinable withthis filtrate in gray water tank 170 or the lagoon. Should the qualityof the separated supernatant liquid 155 not be of sufficient clarity forits intended use, a small secondary phase separation tank (not shown)may be utilized. The volume of floating solids in this vessel will be asmall fraction of the volume in the phase separation tank 150. Thesesolids may be directed to the active filter 160 upon discharge. The nowclarified supernatant liquid may be blended with the filtrate from theactive filter.

The use of the phase separation tank 150 in apparatus 100 and process 5is preferred because it reduces the hydraulic load on the active filter160, thereby improving the overall dewatering efficiency of apparatus100 per unit time.

In an alternative embodiment of the process, the thickened flocculatedmanure slurry from the upper nozzle is not sent to the active filter,but instead to a thickened manure storage vessel (not shown) or a secondlagoon (not shown). The manure is allowed to accumulate and naturallydewater to the extent afforded by the elements and the design of thevessel or lagoon. This embodiment is beneficial to certain farmapplications in which it is preferable to store the manure as athickened slurry that may be rendered pumpable for seasonal spreading.The storage vessel may include an under-drain system that promotesadditional natural dewatering over time. Similarly, the solids recoveredin the active filter may be discharged into such a thickened manurestorage vessel or lagoon and similarly further dewatered. Although it isnot likely that the dewatered manure from the applicant's process willrequire further dewatering, the placement of the dewatered manure onsuch a porous surface will allow for the drainage of precipitation outor the manure to mitigate rewetting to an unacceptable level of moisturecontent for its intended purpose.

Step 50 of method 5, filtration of the floc from the manure slurry isperformed next. The filtration process may be performed by various knownfilters for separating solids to form a liquid stream, such as a drumfilter, a centrifuge, and the like. However, the applicant hasdiscovered that a particular low energy active filter is preferred forperforming the filtering step 50 and dewatering step 60 of method 5. Theactive filter may have one of two forms: a tower form, and a box form.The general principles of the active filter are described and shown inU.S. Pat. No. 5,614,092 of DiLeo, the disclosure of which isincorporated herein by reference. This patent explicitly discloses thetower form of filter; however the principle of operation though thedisruption of the sludge by the manipulation of the bladders in the boxform of filter is substantially the same. The filter is referred toherein as an “active filter,” because of its capability to activelydisplace the filter medium against the solids collected thereupon. Thiscapability makes the filter much more effective in dewatering thefiltered manure sludge to a consistency where it is easily handled.

In one embodiment, apparatus 100 is comprised of one or more of filtershaving the tower form of active filtration, also known as a squeezetower press (STP). One suitable version of a squeeze tower press ismanufactured and sold commercially by Idee e Prodotti S.r.l. of Milan,Italy. In particular, the tower form is sold as the “Squeeze Box” modelin Europe and Asia in a range of sizes having a housing or casing lengthbetween about 3 feet and about 15 feet and associated solids capacitiesof between about 1 cubic feet and about 7 cubic feet. This active filteris modular, such that multiple active filter units may be “ganged”together to make an overall filter system with high capacity.

This active filter is comprised of a base, a filter casing (alsoreferred to herein as a housing) and a locking bonnet. The lockingbonnet is provided with an inlet into the casing for receiving liquidwith solids to be filtered that is supplied by a pump. The cylindricalfilter casing contains the filter medium (typically a filter cloth) andinflatable bladders or tubes disposed between the casing and the filtercloth. The base is comprised of a releaseable hatch used to dischargethe dewatered sludge, and a basin for the collection of the sludge. Thefiltering process takes place inside the cylindrical filter casing. Twosets of three bladders are inflated and deflated, thereby squeezing theaccumulated sludge within the filter medium. The bladder inflation iscontrolled by the manually or by a programmable logic controller. Theactive filtration is carried out in three stages: loading the filterwith liquid containing the solids, squeezing the solid sludge capturedby the filter medium to dewater it, and separation and release of thedewatered solid from the filter medium, and release of it through thehatch at the bottom of the housing.

It will be apparent that other active filters, whether in tower form orbox form, may be used to achieve suitable results. A suitable activefilter is generally comprised a housing, a displaceable filter medium,and means for displacing the filter medium, such means being disposedbetween the housing and the displaceable filter medium. The filterdisplacing means is preferably comprised of at least one, and preferablytwo sets of displacement actuators that can be operated to displace thefilter medium such that it squeezes the sludge contained on the medium.A set of displacement actuators is comprised of at least one actuator,and preferably two or more actuators. Various actuators may be used todisplace the filter medium, including but not limited to hydraulic orpneumatic cylinders, solenoid actuators, cams, and the like. Inflatablebladders are preferred actuators because they are easily integrated intothe filter between the housing and the filter medium, and they aresimple to operate.

Further details on the operation of one or more squeeze tower presses ina filtration application are disclosed in the applicant's U.S.Provisional Application for Patent No. 60/883,315, and in theapplicant's copending U.S. patent application Ser. No. 11/968,240, bothtitled “Method and Apparatus for Treatment of Waste Latex.” Thedisclosures of these United States patent applications are incorporatedherein by reference. Such principles of operation disclosed therein aregenerally applicable to the method and apparatus of the presentinvention.

In the preferred embodiment, the active filter 160 is comprised of oneor more box filters. The box filter is preferred because of itscapability of filtering large quantities of liquid manure waste; it isbetter matched to the scale of operations of a typical large herd dairyor other livestock farming operation. Each of the one or more boxfilters may comprise a removable or semi permanent filter medium in abox-shaped container. The box-shaped container is provided with a liquidfiltrate outlet connectable to filter outlet 288, a plurality ofbladders or other displacement actuators disposed along the horizontalwalls and the bottom of the box, and a filter bag dimensioned to becontiguous with the displacement actuators and to cover appropriateportions of the walls and base of the box.

FIG. 5 is a schematic cross-sectional illustration of a suitable “box”type filter. Box filter 160 is comprised of a box-shaped housing 262having a bottom wall 264, a surrounding side wall 266 that includes adischarge door 267, and a displaceable filter bag 268 disposed withinhousing 262. The discharge door 267 may be hinged vertically ofhorizontally. The discharge door 267 facilitates the emptying of thedewatered sludge or compost from the filter, as will be describedsubsequently herein with reference to FIGS. 8A and 8B. Filter 160 isfurther comprised of at least one inflatable bladder 270, comprised of acentral portion 271 disposed along the bottom wall 264. Alternatively,the filter 160 may include two or more separate bladders extending thelength of the bottom wall 264 interconnected by pneumatic or hydraulictubing (not shown). The bladder 270 or bladders may include an endportion 272 or portions disposed along the end wall 265 opposite thedischarge door 267. The bladder 270 or bladders may also include endportion 274 or portions disposed along the inside face of the dischargedoor 267. Bladder section 274 may be an independent bladder sectioninterconnected to the bladder 270 or bladders by pneumatic or hydraulictubing (not shown). The end portions 272 and 274 of bladder 270 mayextend up the end wall 265 and discharge door 267 of the housing 262less than shown in FIG. 5. The end portions 272 and 274 of the bladderor bladders may consist of a single or multiple sections disposed on theend wall or discharge door of the housing 262 interconnected bypneumatic or hydraulic tubing (not shown).

Alternatively, filter 160 may be comprised of a bottom bladder and oneor more independent end wall bladders in place of end portion 272, andone or more independent discharge door bladders and two additional sideinflatable bladders (not shown) disposed along the side portions (notshown) of side wall 266. If individual end wall or side wall bladdersare used, they may be made independently inflatable and deflatablethrough respective valves 276, 278, and 280, which are controlled byprogrammable logic controller 290 or another appropriate control device.

Alternatively, all bladders may be connected to a single air source andall inflated simultaneously through a single valve 276 as shown in FIG.7; or bottom bladder 271 may be connected to a first air sourcecontrolled by valve 276, and the end and or side wall inflatablebladders may be connected to a second air source such that bottombladder 271 is separately controllable from the end and/or sidewallbladders.

In the embodiment depicted in FIG. 5, the bladder 270 is inflated anddeflated by air supplied and exhausted through valve 276. The cornerportions of bladder 270 may be held proximate to the juncture of the endwall 265 opposite the discharge door and the bottom wall 264 andproximate to the juncture of the discharge door 267 and the bottom wall264 by the lower portion of a support basket or frame 289, which alsosupports the bottom and the vertical sections of filter bag 268 that aredisposed along the bottom wall 264 and the side and end walls 266 of thehousing 262. The profile of the inflated bladder 270, and alternatebladder 274 (if provided separately from bladder 270) is indicated bydotted curves 282, 284, and 286. When the bladder 270 (and alternatebladder 274 if provided separately) is pressurized, the bottom portion271 bulges upwardly while the end portions 272 and 274 bulge inwardly,resulting in the upwardly and inwardly displaced filter bag 269 and thedewatering of the solids therein (not shown).

In one preferred embodiment (not shown), the filter 160 is comprised offirst and second bladders, each having a central portion disposed alongthe bottom wall 264 and end portions disposed along the end wall 265opposite the discharge door of the housing 262. These bladders areformed as elongated tubes oriented parallel to each other and disposedwithin the box-shaped housing 262 in a left-to-right direction in FIG.5. The first and second bladders may be connected and operatedsimultaneously by pressurized air supplied through valve 276, or theymay be connected to individual dedicated and separately controllablevalves (not shown) such that they may be separately actuated in parallelor serially, and in programmed sequences.

As the sludge in the filter 160 is dewatered, at least one outlet 288permits the drainage of filtrate from housing 262. If separatelyoperable bladders are provided in the filter 160, the respectivebladders may be operated sequentially to manipulate the sludge thataccumulates on the filter bag 268. In one preferred embodiment, thefilter 160 is provided with a pair of parallel elongated tubularbladders disposed in filter 160 as shown for bladder 270 of FIG. 5.These bladders are connected to a single air supply and are operated inparallel to displace, manipulate, and disrupt the sludge to dewater it.

To perform the filtration step 50 (FIG. 1) with the active filter 160,waste manure slurry is delivered through inlet pipe 113 as indicated byarrow 299 into the filter 160 from the phase separation tank 160, frommixing tank 110, or directly from pipeline 112 in one mode of continuousoperation. A first portion of filtrate flows through the filter bag 268by the action of gravity and out of outlet 288 as indicated by arrow298. A cake of manure sludge (not shown) is retained by the filter bag268. Subsequently, step 60 is performed in which the sludge isdewatered. The bladder 270 and adjacent parallel bladder (not shown) areactuated to manipulate the sludge cake, resulting in the discharge of asecond portion of filtrate. In particular, the actuation of the bladder270 causes cracks to form in the sludge, thereby providing drainagechannels for filtrate to flow through the sludge, and then through thefilter bag 268 and out of outlet 288.

The bladder 270 and adjacent parallel bladder may be repeatedly inflatedand deflated in programmed sequences, thereby manipulating the sludge onthe filter bag 268 in a manner that maximizes the dewatering thereof.Optimal performance of the system from the standpoint of dewatering hasbeen observed to be achieved with bladder manipulation cycles asfollows. Optimal operating pressure for dairy manure has been observedas 15 to 20 psig. Optimum bladder cycles have been in the range of 45 to90 minutes of inflated time and 45 to 90 minutes of deflated time. Eachmanure stream may have its own optimum characteristic bladder cycletime, however.

Inflation of the bladders opens cracks in the sludge to provide drainagechannels for the filtrate, and deflation of the bladders results in aclosing of the cracks. Then, a subsequent Inflation of the bladdersopens different cracks in the sludge to provide different drainagechannels for the filtrate, and deflation of the bladders results in aclosing of those cracks. In that manner, additional dewatering of thesludge cake is attained, and the sludge is dewatered into a sufficientlydry mass to be readily discharged from the filter bag and suitable forfinal disposition. Such disposition may be as compost or as a solid soilfertilizer, performed by a manure slinger spreader or compost blender195 or other beneficial use or as high solids feed material for asuitably designed anaerobic digester.

One preferred mobile container for filtering the flocs and dewateringsludge is the “Dry Box 15000” active filter manufactured and soldcommercially by Idee e Prodotti S.r.l and sold in the United States byInnovative environmental Products, Inc. The large scale mobile boxactive filter may be provided in a “roll-on” and “roll-off”configuration for overland transportation by truck. This may beadvantageous hauling the recovered manure solids over longer distancesfor its final disposition.

In one embodiment (not shown), the applicant's apparatus 100 or 101 maybe comprised of multiple box active filters 160. If multiple box activefilters are used, they may be operated in sequence, with a first boxreceiving floc-containing liquid, then a second, and then a third, etc.receiving the liquid. In this embodiment, the slurry may requirechemical treatment between each active filter to flocculate theremaining unfiltered particulate matter. Alternatively, the boxes may beoperated in parallel, with all of them receiving the floc-containingliquid.

The first and second portions of filtrate may be discharged to eitherthe gray water tank 170, the lagoon 175, the ultraclarification unit180, or the ozone sterilizer 190. The displacement actuators may becycled through multiple inflation and deflation cycles as describedpreviously herein to “work” the sludge cake, such that additionalportions of filtrate are discharged. Following the initial fill of anddewatering of the dry box, a second fill of the identical format maytake place. Subsequent fills may proceed until the desired volume ofmanure floc containing liquid has been added to the box in order toachieve the desired final fill volume and total dry matter.

Although the applicant's chemical treatment of the manure containingliquid described herein is preferred prior to performing the filtrationprocess described herein, alternate flocculation chemical regimens areknown to form a suitably dewaterable manure sludge. Such regimens mayprovide for acceptable filtration functionality within the dry box, orpotentially in a squeeze tower press type of active filter. However, thethroughput, the level of solids in the dewatered cake, the ability toremove or otherwise discharge and process the solid waste manure cake,and the clarity of the filtrate may be poorer than with the proposedchemical reagent regimen of the present invention. Nonetheless, thehandling of the flocs and the manipulation of the manure sludgefollowing treatment by any chemical regimen, according to the methods ofoperating the active filtration equipment described herein areconsidered within the scope of the present invention.

Without wishing to be bound to any particular theory, the applicantbelieves that a significant factor in the success of the chemicaltreatment regimen and the gentle handling of the floc in the processvessels and/or piping, is the gentle manipulation of the floc within theactive filtration equipment, in either the squeeze tower press form, orthe dry box form. Alternate means of such gentle manipulation anddisruption of the solids cake will have the same result and areconsidered within the scope of the present invention. It is noted that arotary drum vacuum filter may offer similar dynamic action on thesludge. However, for the processing of liquid manure waste, it has beendetermined that the dry box version of the active filter is the mosteconomical separation system based upon the initial cost and dailymanure separation capacity. The dry box active filtration equipment inwhich the displacement actuators are comprised of inflatable bladders ishighly portable and only requires a small volume of low-pressurecompressed air for operation of the bladders. Additionally, theequipment offers significant energy and capital savings, as well asincreased operational flexibility over other filtration systems.

Any chemical regimen combined with the phase separation tank as aprecursor to a mechanical separation device equipment with the includedaccommodations for limitation of hydraulic disruption of the flocculatedmanure described herein are considered within the scope of oneembodiment of the present invention.

It has been observed at commercial scale when processing dairy manurewhich has not been pre-processed in an anaerobic digester, and which hasbeen separated from a major portion of the large bedding solids, themanure solids do not adequately dewater within the filter housing 262through the depth of the manure mass. Without wishing to be bound by anyparticular theory the applicant believes the mucous cells within nondigested dairy manure form a gelatinous mass when the manure iscoagulated and flocculated and allowed to set within the housing 262.This mass does not adequately dewater within the standard commercialconfiguration of the housing. To a lesser degree the solids within thefiltrate from separated digested dairy manure perform similarly,although apparently not as a result of the presence of mucous cells asthey would have been significantly reduced in the digestion process.

It has also been observed by the applicant that elevated levels of themetal chloride coagulant ferric chloride mitigates the formation of thegelatinous mass to varying degrees dependent upon the source and speciesof origin of the manure. These elevated levels have been in the range of100% to 200% over the normal dosage levels of the metal chloride.Polyaluminum chloride has also provided similar effects. However thepresence of the aluminum contamination within the manure mass is notuniformly acceptable to the agricultural community

The selection of the method or methods within the applicant's process toachieve the optimum dewatering is site (i.e. manure) specific.Disposition of the dewatered manure mass, economic factors, availabilityof amendment materials and the like are the parameters evaluated todetermine the optimum method.

In order to achieve adequate dewatering of the manure sludge in thefilter 160, a preferred embodiment includes a method to add and blendcontrolled amounts of amendment materials to the manure before it entersthe filter housing. A description of the amendment materials additionprocess is provided subsequently herein in conjunction with addition ofcomposting amendment materials. These amendment materials act to disruptthe nature and stability of the gelatinous or poorly dewaterable masswithin the housing and promote porosity within the mass during thedewatering process. This increased porosity allows for more effectivedewatering of the mass during the operation of the disruptionmechanisms. The insertion point of the amendment materials may be movedupstream in the process prior to the chemical addition points, shouldparticulate contaminants within the particular amendment materialsrequire some level of chemical treatment to prevent these contaminantsfrom blinding the filtration fabric in the housing.

As an alternate to or in addition to the addition of the amendmentmaterials a further embodiment includes a method to direct air into andthrough the bed of the dewatering or composting manure. This air willpromote air drying of the manure solids in addition to the drainagepromoted by the repeated disruption of the manure mass within thehousing by the bladders.

As an alternate to or in addition to the above, elevated levels of themetal chloride coagulant ferric chloride may be added to the manurestream at the indicated point of injection into tank 110 or pipe line112 to mitigate the formation of the gelatinous mass in the dewateringmanure.

Optional step 65 of method 5, a final “polishing separation,” i.e.removal of additional solids from the filtrate discharged from activefilter 160 or from the bottom outlet 156 (FIG. 4) of the phaseseparation tank, may be performed next. The polishing filtration processmay be performed by various known filters for performing fine particlefiltration. However, a particular low energy dynamic filter is preferredfor performing step 65 of method 5, that being the aforementionedsqueeze tower press active filtration, as disclosed in U.S. Pat. No.5,614,092 of DiLeo, and further described herein. Depending upon thedownstream process requirements, polishing of the filtrate may insteadbe successfully completed in a dry box.

Ultraclarification unit 180, which in addition to active filter 160, ispart of the overall filtration system 260, is used to perform step 65and may include one or more squeeze tower presses (not shown). Thesqueeze presses may be operated in sequence, with a first pressreceiving floc-containing liquid, then a second, and then a third etc.receiving the liquid. In this embodiment, the slurry may requirechemical treatment between each filter to flocculate the remainingunfiltered particulate matter. Alternatively, the presses may beoperated in parallel, with all of them receiving the floc-containingliquid. The flocs in the liquid are retained in the filter mediumcontained therein as a semi-solid sludge, while a first portion offiltrate is discharged to gray water tank 170 or lagoon 175, or morepreferably, to ozone sterilizer 190, in which the filtrate is convertedto bacteria-free water suitable for reuse as wash down water for milkhouse or other livestock operations, or livestock foot bath flush waterin place of cupric sulfate solutions, or in certain instances as potablewater for livestock. The solid manure floc captured in the squeeze towerpress(es) is discharged to a manure slinger spreader or compostingblender 195 for subsequent use as compost or a solid fertilizer. Detailson the operation of a squeeze tower press are disclosed in theapplicant's aforementioned copending U.S. Provisional Application forPatent No. 60/883,315, “Method and Apparatus for Treatment of WasteLatex,” at pages 23-32 and in FIGS. 3 and 4; and in the applicant'saforementioned copending United States patent application No. 11/968,240at pages 37-46 and in FIGS. 3A, 3B, and 5. Such operational details aregenerally applicable to the present invention.

The squeeze tower press has also been utilized as the active filter 160in apparatus 100. In general, the filtrate from the squeeze tower pressis lower in suspended solids and higher in clarity than that dischargedfrom the dry box active filter. The filtration medium in the squeeze boxmay be of a much finer mesh than can economically be provided for oroperated within the dry box filter. Additionally, it has beendemonstrated that the treatment of the filtrate from a dry box filterthrough an identical or similar chemical process as described herein,and then through a squeeze tower press, or under optimum conditionsthrough only a dry box filter, produces a final filtrate that hasessentially total phosphorous nutrient solids removal from the filtratein the range of about 95 to 99 weight percent. Furthermore the suspendedsolids are removed from the liquid manure stream at a rate of 94 to 99weight percent.

The manure sludge resulting from the use of the dry box filter istypically in the range of about 12 to 20 weight percent dry solids. Themanure sludge resulting from the use of the squeeze tower press istypically in the range of about 9 to 22 weight percent dry solids.Higher dry solids may be achieved, but the resilient nature of thedewatered manure sludge makes automated discharge of the sludge from thesqueeze tower press difficult and time consuming. Additionally, theperformance of the squeeze tower press is sensitive to over-pressurizingthe dewatered manure solids and over-feeding the separation equipment.Breakdown of the floc and/or packing of the filter have been experiencedfrom these operating conditions. The extent of these problems vary tosome degree with the type of manure being processed. The applicant hasobserved that liquid manure with percentages of bedding solids below therange of one to two percent by weight do not demonstrate this problem.

The degree of dewatering from the process is dependent upon severalfactors such as the dewatering period and/or the presence of inert orlarge particulate matter in the manure. Manure that has not been firstprocessed by a manure mechanical separator 106 will achieve a higherdegree of dewatering at a faster rate than the “filtrate” from such aseparator. As discussed previously, the applicant believes thatadditional large or inert particulate matter remains in the manurestream and provides for enhanced filtration. Addition of a small portionof separated solids from a manure separator to the separator “filtrate”that is being processed within the applicant's process will enhance thefiltration. Addition of this material may be added to the slurry inbatch or continuous mode.

The applicant's method 5 and apparatus 100 and 101 are amenable toautomated process control with the addition of simple instrumentationand control loops. FIG. 6 is a schematic illustration of one embodimentof the applicant's waste treatment apparatus including such processcontrol components. A pH meter 111 with a probe disposed in pipeline 112may be used to monitor the pH of the waste manure liquid in thepipeline. The value of the pH in the pipeline may be used by aprogrammable logic controller (not shown) to control the rate ofaddition of reagent A.

The phase separation tank 150 (PST) may be employed in severalembodiments of the process. Referring further to FIGS. 4 and 6,preferably the PST 150 is inserted in the process just prior to the drybox active filter 160. The diluted and chemically treated manure slurryenters the tank 150 at a mid point port 152 approximately within themiddle third of the height of the tank. As the slurry enters the tank,the flocculated manure will tend to rise to the top of the tank andfloat on top of the supernatant liquid. The supernatant liquid, withadequate residence time, will liberate essentially all of theflocculated solids and be very low in suspended solids, potentially aslow as the filtrate from the dry box.

The supernatant liquid is drawn off of the bottom portion of the tankwith throttling at a controlled rate. This rate is set such that thethickened flocculated solids 157 at the top of the tank flowcontinuously out of the upper outlet at a constant rate with only minorfluctuations in the tank level.

The supernatant liquid may be drained and/or pumped to the gray watercollection tank 170 or to lagoon 175. The supernatant liquid istypically as clear as the filtrate from the dry box active filter 160,so it is typically combined with said filtrate after the dry box. Thethickened manure solids 157 flow out of the upper outlet nozzle of thePST and drain to the dry box. This mechanism reduces the hydraulic loadon the dry box, thereby improving the dewatering efficiency measured asa function of time.

One exemplary phase separation tank 150 will now be described in moredetail. In one embodiment, the phase separation tank 150 is acylindrical tank. The nozzle 156 for the draw off of the supernatantliquid from this tank is preferably located at least 6 inches above thebottom of the tank 150 to prevent entrainment of any settled sediment(such as sand fines or other sediment that is more dense than water) inthe liquid. The bottom of the tank 150 is preferably pitched to a bottomclean out valve 149 in order to allow for periodic cleaning of thesediment from the bottom of the tank 150.

The agitator 159 within the tank serves to keep the slurry moving withinthe tank and to prevent the formation of large gelatinous masses thatwould not exit the tank nozzles. The blades of the agitator arepreferably set in the lower, middle, and upper thirds of the tank. Thebottom agitator blade 159A is preferably at least 24 inches above thebottom of the tank. This is preferred to allow for adequate stilling ofthe supernatant liquid and to prevent entrainment of any sedimentationfrom the bottom of the tank into the supernatant liquid. The top blade159C of the agitator is preferably at or just below the level of the topoutlet nozzle. The three-agitator mixer 159 as shown in FIG. 4 ispreferred, although a single agitator mixer that provides gentlecirculation of the slurry in the PST 150 to assist phase separation maybe suitable.

The applicant has observed that for some manure wastes, the density ofthe flocculated solids 157 is greater than the density of thesupernatant liquid 155. Accordingly, the phase separation of the solids157 and the supernatant liquid 155 occurs in a manner opposite to thatshown in FIG. 4, i.e. the solids 157 settle toward the bottom region ofthe tank 150. In this situation, the flocculated solids 157 aredischarged through lower outlet 156, and the supernatant liquid 155 isdischarged through upper outlet 153. To accommodate this situation, theapparatus 100/101 (FIGS. 2 and 3) may be provided with selector valvesand additional piping (not shown) to route the effluent stream withsolids 157 to the filter 160, and the supernatant liquid to the graywater tank 170 or lagoon 175 of the ultraclarification unit 180,regardless of which of outlets 153 and 156 they are discharged from. Asdiscussed above the diameter of the flocculated solids handling pipe enroute to the filter housing must be of sufficiently large diameter toprevent plugging and limit hydraulic disruption of the flocculatedmanure as well as accommodate the addition of amendment materials.

Should the quality of the separated supernatant liquid requireadditional treatment in order to accommodate an intended use, it may becollected in a small secondary phase separation tank (not shown). Thevolume of floating solids on top of the liquid in this vessel would be asmall fraction of the volume in comparison to the floating sludge 157 inthe phase separation tank. The solids in the small secondary phaseseparation tank may be drawn off through the top exit fitting anddirected to the active filter 160 upon discharge. The now clarifiedsupernatant liquid may be blended with the filtrate from the activefilter 160. Alternatively the filtrate may be retreated with the processtreatment chemicals and filtered through a squeeze tower press oradditional box filter.

Based upon experimental trials, the optimum tank configuration appearsto be three to five feet in diameter by 10′ to 12′ high. The pitched,wide profile agitator blades 159A/159B/159C are set approximately 24inches off the bottom of the tank, near the middle 5′ foot level andnear the 8′ level of the tank. The agitator speed will vary with thenature of the solids within the manure slurry; however 20 to 30 rpmappears to be an optimum speed. The optimum flow rate for thisconfiguration of tank appears to be in the range of 30 to 60 gallons perminute, as five to 10 minutes, and in some cases as much as 20 minutes,appears to be the optimum residence time to achieve the separation ofthe clarified supernatant liquid phase from the thickened flocculatedsolid slurry phase.

Not wishing to be bound by any particular theory, the applicant observedthat the performance of the separation tank appears to be a function ofthe chemical concentrations within the liquid manure, the concentrationof the manure, and the type and source of the manure. In certaininstances where the conditions are not able to be optimized for physicalor economic reasons, the separation tank may simply serve as a residencetank utilized to ensure that the reaction between all of the reagentsand the liquid manure, and the resulting flocculation is complete.

In a further embodiment, the applicant's apparatus and method may beconfigured to produce compost material directly within the activefilter, instead of in composting blender 195. FIG. 7A is a schematiccross-sectional illustration of a “box” type filter including means forproducing compost from the sludge collected therein. Filter 360 of FIG.7A is similar to filter 160, but is shown as comprising a firstelongated inflatable bladder 270 comprised of a central portion 271disposed along the bottom wall 264 and a first end portion 272 disposedalong the end wall 265 of the box housing 262. Bladder 270 may furthercomprise a second end portion 274, or alternate portion 274 on thedischarge door of the housing 262 provided as a separate bladder. Filter360 is preferably comprised of a similar second elongated tubularbladder (not shown) oriented parallel to bladder 270 and disposed withinthe box-shaped housing 262 in a left-to-right direction in FIG. 7A. Bothof such bladders may be connected and operated simultaneously bypressurized air supplied through valve 276 under the control ofprogrammable logic controller 290.

Filter 360 is configured such that it may be utilized as a compostingvessel for the manure upon completion of the dewatering phase. Filter360 may also be suitable for composting of municipal waste watertreatment plant sludge. In addition the same configuration may beutilized to achieve the supplemental dewatering of the manure discussedabove as it relates to mitigation of the problem of gelatinous masses ofsludge from non digester manure or poorly dewaterable manure from manureseparator filtrate. Variations between the composting operation and thesupplemental dewatering operation are identified herein. The means forproducing compost from the sludge includes at least one ventilating fan362, at least one probe 364 for measuring the temperature of the sludge,and may include at least one probe 366 for measuring the moisturecontent of the sludge. The means for supplemental dewatering of thesludge includes at least one ventilating fan 362, and at least one probe366 for measuring the moisture content of the sludge. The sensors 362and 364 are contactable with a volume enclosed within the firstdisplaceable filter medium, and thus are contactable with the dewateredsludge 8 contained therein. The ventilating fan 362 is in communicationwith the space between the housing 262 and the displaceable filtermedium 268 of the filter 360 through a duct 368, which may be connectedto the liquid outlet 288 in the housing 262, or to a separate port. Theduct 368 is preferably a flexible duct commonly used in air handlingoperations. Duct 368 is connected to the housing in a horizontal ordownward direction and contains a shut off valve (not shown) so as notto become flooded with filtrate during the dewatering process, with itbeing understood that duct 368 is shown oriented downwardly in FIG. 7for the sake of simplicity of illustration.

During the composting step or the supplemental dewatering step of theapplicant's process, fan 362 is operated, forcing outside air throughduct 368 and into the box housing 262 as indicated by arrow 399 alongthe bottom wall 264 and the lower portions of the side wall 266 of thebox housing 262. The pressurized air passes around the bladder 270,through the filter bag 268, and into the dewatered manure sludge 8 asindicated by serpentine arrows 298. The flowing air continues topercolate upwardly through the dewatered sludge 8, and out through aporous and permeable or vented waterproof and partially insulating cover370, which is secured over the open top of the box housing 262.

The supply air to the housing may be heated during cold periods toenhance drying and to mitigate freezing of the manure mass. This may beaccomplished with a gas fired air heater or heat exchanger (not shown)or through the use of a heat exchanger or other method (not shown) torecover supplied process heat or rejected heat from adjacent orproximate equipment. The heating device may be installed into the inletducting or the outlet ducting of fan 362.

The air supply to the housing 160 may enter through an alternate,dedicated entry nozzle in the wall of the housing. Within the housing inthe space between the filtration fabric and the housing bottom wall theair may be delivered to the close underside of the dewatering orcomposting manure. This may be done through a matrix of distributionpiping within the space between the bottom wall and the filtrationfabric in the housing (not shown). The air may be delivered from thedistribution piping to just beneath the bed of dewatering or compostingmanure through small nozzles or perforated piping or the like (notshown).

One suitable membrane or cover 370 is the W.L. Gore and Associate'sGORE™ Cover System. The fabric of this system is comprised of amicroporous membrane that is laminated between two ultraviolet resistantsupport fabrics. The cover is waterproof and windproof to protectcomposting or dewatering material from the elements, but it is alsopermeable to water vapor, allowing moisture to be released, along withCO₂ generated from composting. The cover also provides some insulatingproperties that help maintain composting temperatures. This cover 370may be mechanically supported over the top of the housing 262 asindicated in FIG. 7A in solid line format, or cover 370 may be tetheredto the outside of housing 262 and allowed to drape down into the housingand rest upon the composting materials, as indicated in FIG. 7A indotted line format.

In the operation of the applicant's composting filter, it is preferablethat all of the pressurized air delivered by fan 362 is flows onlythrough the sludge 8. However, absent any countermeasures to thecontrary, a significant portion of the pressurized air may bypass thedewatered sludge 8, and instead flow upwardly along the side walls 266,the end wall 265 and the door 267 where the supporting framework holdsthe filter medium 268 separate from the wall surfaces. The bypass flowmay escape out through the portion of the filter medium 268 that is notcovered by sludge, and/or through other passageways near the top of theframework. Accordingly, in one preferred embodiment, the applicant'scomposting filter is further comprised of means to block such bypassingairflow, thereby forcing substantially all of the airflow to passthrough the dewatered sludge and facilitate the composting orsupplemental dewatering thereof.

FIG. 7B is a detailed cross-sectional illustration of a sidewall regionof the “box” type filter 360 of FIG. 7A showing an air flow blockinginsert disposed between the filter medium and the sludge collectedtherein. Insert or panel 310 is comprised of a thin planar sheet 312 ofmaterial that extends downwardly along the inside of side walls 266between the sludge 8 and the filter cloth 268. A hanger channel 314comprised of short horizontal section 316 and vertical section 318 isformed at the upper end 320 of the sheet 312 for engaging with the upperedge 263 of the side wall 266. Prior to the beginning of the compostingof the sludge 8, the insert 310 is forced down along the filter cloth268. Insert 310 may cover substantially the entire area of the side wall266, or multiple inserts 310 may be provided, such that the set ofinserts covers the entire area of the side wall 266. In like manner,corresponding air flow blocking inserts are similarly fitted along thedoor 267 at the end of the filter box housing 262. For elimination ofbypassing aeration air at the end wall 265 of the housing 262 oppositethe discharge door the vertical section 272 of the bladder may beexcluded with insert 310 being used. Alternately, if the verticalsection 272 of the bladder is present, the end wall 265 may be coveredwith a flexible non permeable plastic membrane prior to initiation ofthe filling and dewatering operation.

In this manner, the air flow blocking inserts 310 and the flexiblefabric at the end wall 265 prevent the air from short circuiting aroundthe composting material 8 and out through the sections of the filtrationfabric 268 not covered by composting material and/or through otherpassageways near the top of the underdrain structure supporting thefilter cloth. The air blocking panels 310 may be fabricated of rigidplastic materials such as CPVC or polypropylene or any other rigidmaterial that will maintain its structural integrity at the compostingtemperatures, and provide sufficient rigidity to enable forcing thepanels down along the filter cloth 268 into the desired position. Theedges of the panels 310 may be deburred and/or radiused to preventcutting of the filter cloth. The top portion of the air blocking panels310 may be vented or inserted in such a manner to allow for the passageof a small volume of ventilation behind the panels. Alternately acontiguous top rail for the support structure of the underdrain system(not shown) may be constructed which would include ports to accommodatethis venting. Numerous alternate means of blocking the bypassing of theair flow may include flexible materials which drape down the face of theexposed filtration fabric 268 as the mass of composting manure shrinksexposing more surface area of fabric 268. Thus the blocking of thebypassing aeration air by any such means is to be considered within thescope of the present invention.

The fan may also be configured by providing additional ducting andvalves to withdraw air from the space between the housing 262 and thedisplaceable filter medium 269 of the filter, instead of or in additionto supplying air thereto. This functions to provide downward ventilationthrough the compositing material. This functionality may be utilized incases where odor control and other beneficial aspects of the downwardair flow are needed.

Referring also to FIG. 2, and in one embodiment, the applicant'sapparatus 100 is provided with a source 380 of composting or dewateringamendment materials. The source 380 may be a hopper, a bin, or othersuitable container. The amendment material may be e.g., wood chips, orother materials to be described subsequently herein. The apparatus 100is further comprised of an auger (not shown) or other conveying meansfor delivering the amendment materials to the filter 360. In thepreferred embodiment, the auger delivers amendment materials from thesource 380 through a duct 382 that is connected to the inlet pipe 113through which the flocculated waste manure flows to filter 360. In thatmanner, the amendment materials may be uniformly distributed throughoutthe waste manure prior to its entering the filter 360.

The supplemental dewatering step 300 of the applicant's process will nowbe described with reference in particular to FIGS. 1, 2, and 7.Referring first to FIG. 1, the applicant's process 5 is performed suchthat steps 50 and 60 are completed, i.e. filtration and dewatering ofthe manure sludge in the filter 360 to the extent possible. The filter360 is filled with the semi dewatered manure sludge to the desiredlevel, which is sufficient to cover most of the free area of the filtercloth 269 along the side wall 266 of the box filter housing 262. Duringthe step 50 of delivery of flocculated waste manure to the filter 360,dewatering amendment material may also delivered through duct 382 andcombined with the flocculated waste manure. The semi-dewatered sludge 8in the filter 360 may thus be a mixture of manure and dewateringamendment material.

These amendments typically consist of materials such as wood chips. Inaddition, these materials may include straw, whole or shredded plantstems, stalks, cobs, husks, and the like and/or dewatered manure solidsfrom high energy dewatering equipment such as screw presses, poultrylitter and the like. These materials may be added to the manure streamimmediately prior to discharge point of the manure into the activefilter box as described previously herein. The required amendmentmaterial and proportion of addition depends upon the type of manurebeing processed.

When the active filtration dewatering step 60 is complete and nosignificant flow of filtrate out through outlet 288, the supplementaldewatering step 300 is begun. The fan 362 is started. Fan 362 is drivenby motor 372, the speed of which may be controlled by variable speeddrive (VSD) 374, which is in communication with and operated byprogrammable logic controller (PLC) 290 or other suitable speed controldevice. The fan 362 is operated for a period of time at a first speed topartially dry the dewatered sludge to a desired predetermined value thatresults in its effective end use. The moisture content of the sludge 8is measured by moisture sensor 366, which is in communication with PLC290 or by manual means. Once the desired level of dryness of the manuresludge 8 is achieved, the fan is shut down. The dewatered sludge may bedischarged from the filter 360 for final disposition.

The composting step 301 of the applicant's process will now bedescribed, also with reference in particular to FIGS. 1, 2, and 7.Referring first to FIG. 1, the applicant's process 5 is performed suchthat steps 50 and 60 are completed, i.e. filtration and dewatering ofthe manure sludge in the filter 360. The filter 360 is filled withdewatered manure sludge to the desired level, which is sufficient tocover most of the free area of the filter cloth 269 along the side wall266 of the box filter housing 262. During the step 50 of delivery offlocculated waste manure to the filter 360, compost material may alsodelivered through duct 382 and combined with the flocculated wastemanure. The dewatered sludge 8 in the filter 360 may thus be a mixtureof manure and compost amendment material.

When the dewatering step 60 is complete, and no significant flow offiltrate out through outlet 288, the composting step 301 is begun. Thefan 362 is started. Fan 362 is driven by motor 372, the speed of whichmay be controlled by variable speed drive (VSD) 374, which is incommunication with and operated by programmable logic controller (PLC)290, or other suitable speed control device. The fan 362 is operated fora period of time at a first speed to partially dry the dewatered sludgeto a desired predetermined value that results in effective composting.The moisture content of the sludge 8 is measured by moisture sensor 366in communication with PLC 290, or by manual means. The desired moisturecontent is dependent upon the type of manure in the filter 360, thecarbon to nitrogen ratio of the manure, and the amount (if any) ofcompost material added to the manure during the filtration step 50.

Once the desired level of dryness of the manure sludge 8 is achieved,the fan VSD control 374 may be set to control the flow of air to the boxwhich will in turn maintain the temperature of the manure solids atpredetermined values or value ranges for predetermined time period thatis effective for composting of the particular manure. The temperature ofthe sludge 8 is measured by temperature sensor 364, which is incommunication with PLC 290. It is also noted that during the compostingstep 300, the inflation and deflation of the bladder 270 of the activefilter 360 may be continued, such that the sludge therein is continuallydisrupted, In that manner, more uniform airflow, moisture content, andtemperature set points are maintained within the composting sludge 8.When the time period is complete, the composting step is terminated. Thefan 362 is run until the compost is cooled to a desired temperatureand/or shut down, and the air flow through the composted sludge 8ceases. The composted sludge may be discharged from the filter 360 forfinal disposition.

In the case of most manure streams emanating from dairy or swineoperations, the level of dryness resulting from the standard operationof the active filter dewatering cycle will provide a moisture contentand/or porosity within the manure which may not be satisfactory for theinitiation of composting biological activity. In order to provide forthe manure mass to achieve the required moisture content, there may be aneed to add “amendments”, i.e. suitable composting materials to themanure. These materials also improve the porosity of the manure bed,which promote better aeration of the bed and thereby enhance thebiological activity therein.

These amendments typically consist of materials such as wood chips. Inaddition, these materials may include straw, whole or shredded plantstems, stalks, cobs, husks, and the like and/or dewatered manure solidsfrom high energy dewatering equipment such as screw presses, poultrylitter and the like. These materials may be added to the manure streamimmediately prior to discharge point of the manure into the activefilter box as described previously herein. The required amendmentmaterial and proportion of addition depends upon the type of manurebeing processed. In general, amendment levels are expected to be in therange of 0.5 to 1 pounds of dry amendment per dry pound of manure solidsin the liquid manure stream. The relationship between baseline moisturecontent of a particular dewatered manure slurry without amendment andthe required level of amendment to render that dewatered slurry suitablefor composting is generally known to those skilled in the art. Ingeneral, the moisture content of the manure and amendment blend is inthe range of about 40 to about 65 weight percent solids in order forcomposting biological activity to commence and be sustained.

Temperature vs. time cycles for composting are also known to thoseskilled in the art. The speed of the aeration fan 362 is set to controlthe temperature in the composting sludge 8 through the PLC 290 tomaintain the desired temperatures and hold periods for optimummesophilic (20-40° C.) and the thermophillic (50-70° C.) bacterialaction associated with the particular manure. These terms “mesophillic”and “thermophillic” refer to specific types or composting families ofbacteria which are active at these respective temperatures.

The amendment may be added to the flocculated manure stream through anopening in the supply pipe 113 or into an enlarged section of the supplypipe 113 that feeds the filter 360. Alternate locations for the additionof the amendment are considered to be less preferable. Introduction ofthe amendment too far up stream of the filter 360 may promote excessiveabsorption of water into the amendment materials, thereby reducing theireffectiveness in moisture adjustment and porosity improvement.

Suitable means of metering the amendment into the flocculated manurestream may include a metering screw or auger as recited previously, apneumatic blower, a metering conveyor, or other similar device. Theupstream controls of the applicant's NTP systems 100 and 101 provide asteady flow rate and consistency of the flocculated manure stream. Theamendment metering equipment may be set to match the manure flow throughfeed pipe 113 to achieve the desired proportion of amendment in themanure sludge 8.

During the composting cycle the repeated cycling of the bladders beneaththe manure cake promotes the aeration of the sludge 8, which isbeneficial to efficient aerobic aeration. The introduction of theventilation air ensures the availability of oxygen for the aerobicbacteria, and also serves as a control mechanism for temperature topermit cooling the sludge 8; and alternately, by reducing the air flow,to permit the temperature to rise for stimulation of the bacteria in thesludge 8.

An improved box filter which has a filter medium that is longer lastingand easier for operating personnel to use, and which can be used withthe applicant's waste manure treatment method and apparatus will now bedescribed. It is first noted that the operation of the box filter 160described herein and shown in FIG. 5 includes the installation of alarge filter cloth 268 having various tucks as needed to form abox-shaped bag, which is folded up on to the rear door of the box toprovide filtration at the door portion 267 of the filter 160 and toclose off the rear of the filter bag. The filter cloth 268 of the boxfilter 160 has generally been a one-use disposable item in applicationsof the box filter 160. However, the performance of the chemistry in theapplicant's NTP system allows for reuse of the filter cloths, as thecloths are not typically blinded by the manure solids after severaluses. In order to reuse the standard filter cloth 268 of the filter 160of FIG. 5, the cloth 268 must be folded up at the rear door by operatingpersonnel for each repeated use. This is an unacceptable procedure froma health and safety perspective. In order to accommodate the repeatedreuse of the filter cloths, a means to avoid or minimize personnelcontact with the fabric at the rear door is necessary.

To meet this need, the applicant has invented an improved box filterwith a filter medium that can be repeatedly reused, and easily refittedwithin the filter housing after the emptying of sludge or compost fromthe filter, as shown in FIGS. 8A-8C. FIG. 8A is a schematiccross-sectional illustration of a “box” type filter with improved filtermedia. FIG. 8B is a detailed cross-section of the juncture of a sidewall and a side door of the box filter of FIG. 8A, the detail showingthe corner portion of the filter taken along the line 8B-8B in FIG. 8A.FIG. 8C is a view of a means for fastening the filter medium to thevertical edges of the side wall of the filter, the detail showing thefastening means within the ellipse marked “8C” in FIG. 8B.

Referring first to FIG. 8A, box filter 460 is comprised of a box-shapedhousing 462 having a bottom wall 464 and a surrounding side wallcomprised of panels 466, 468, 470, and a fourth panel not shown.referring also to FIG. 8B, panel 470 of the surrounding side wall isconfigured as a door hingably attached to side wall 466, such that panel470 can be deployed to an opened position by swinging to the side, andthen closed again, as indicated by arcuate arrows 499 in FIG. 8B.Alternately the panel 470 may be hingably attached to the top of sidewall 466 and its opposite panel (not shown) such that panel 470 can beupwardly deployed to an opened position, and then closed again.

Filter 460 is further comprised of a displaceable filter cloth 472disposed within housing 462. The filter cloth 472 is made of a suitablydurable and chemically resistant fabric such as e.g., woven or non wovenpolypropylene fabric. The four sided pocket-shaped filter cloth 472 isprovided with a shorter than standard length at its end that isproximate to the door panel 470. The length is just sufficiently long toextend as a flap 492 a short distance beyond the vertical edge 474 ofpanel 468, and the corresponding opposite panel not shown; and beyondthe horizontal edge of the bottom wall 464 that is contiguous with doorpanel 470 when the filter cloth 472 is properly installed and secured tothe inside of the box-shaped housing 462. A suitable length for flap 492is about 6 to 12 inches, although the distance may vary depending uponthe construction of the filter box housing 462.

Along the side panel 468 and its opposite (not shown), this extra lengthor flap 476 of filter cloth 472 is wrapped around the ends and tetheredto the exterior surfaces of the panels with suitable fastening means.Referring again to FIG. 8B, the flap 476 of filter cloth 472 extendsoutwardly and back along the outer surface 478 of panel 468. The flap476 is secured to the outer surface 478 by suitable fastening means 480such as that depicted in FIG. 8C. Referring to FIG. 8C, the fasteningmeans is a clip 480 comprised of plates 482 and 484 adjustably securedto each other by threaded fastener 485 and nut 486. Clip 480 is furthercomprised of tension springs 487 and 488, and gripping pads 489 and 490.When nut 486 is tightened on fastener 485, the gripping pads 489 and 490pinch flap 476 between them, thereby securing it to the vertical outersurface 478 of panel 468. It will be apparent that may other similarclips may be used in lieu of clip 480. Should flap 476 be of excessivelength, the excess may be folded and tucked into clip 480 with furtherexcess material left to drape outside of the clip and be cut off ifnecessary.

The door panel 470 is provided with a semi permanent flexible filterfabric 471 that is fastened to the “under drain system” (i.e. the filtercloth-supporting framework 473) at the rear door. This filter fabric isa suitably durable and chemically resistant fabric such as e.g., wovenor non woven polypropylene fabric. The filter fabric is fastened to theunder drain system 473 at the rear door 470, such as with bars (notshown) that pinch and seal off the edges of the fabric to the side wallsof the filter box. A fabric manipulation mechanism such as a bladder asdescribed herein may optionally be positioned behind the rear doorfiltration fabric 471 to ensure disruption of the filter cake on thefabric and keep the surface thereof from being blinded with sludgeparticles. This capability will also serve to knock off problematicmanure cake when emptying the box filter 460.

Referring again to FIG. 8B, the surfaces of the door panel 470 which arecontiguous with the vertical edges of the side walls 468 and itsopposite and bottom wall 464 are fitted with a flexible gasket 475 whichis compressed when the door 470 is closed and properly latched to form awater tight seal. The sealing surfaces of the side walls 468 and itsopposite and bottom wall 464 may be fitted with a gasket 477 similar tothe gasket 475 on the rear door. When there surfaces are compressedtogether by the closing of the door panel with the fabric of filtercloth 472 captured between them, they form a water tight seal andfurther secure the filter cloth within the box housing 462. It is notedthat for simplicity of illustration, the gaskets 475 and 477 are notshown as being crushed into each other and pinching the flap 476 offilter fabric 472 in FIG. 8B, but such gaskets are crushed together whenthe door 470 is fully closed.

In the operation of filter 460, when the manure sludge has beendewatered and is ready for discharge from filter 460, the rear door 470is opened as indicated by arrow 499 and the manure sludge is dumped fromthe box. The box filter 460 is preferably mounted as a “dump box” on atruck or other suitable elevating dumping structure, and is tiltable sothat the bottom 464 of the box housing 462 is tilted downwardly towardsdoor 470, so that the manure sludge simply falls out of the box housing462. The filter cloth 472 remains tethered to the side lips of the boxhousing 462 and drapes across the bottom end when the charge of manureis emptied. The rear door 470 is then closed and latched, and the fabricis once again compressed between the rear door seal(s) 475 and 477 toform the water tight seal. This procedure may be repeated until thefilter cloth 472 is no longer useable and requires replacement. At thattime the fabric fastening means are released to allow for the removal ofthe filter cloth 472. The filter cloth 472 is then removed and replaced.

The applicant's methods and apparatus configurations described hereinand shown in FIGS. 1-8C are advantageous with respect to severalenvironmental considerations. Referring again to FIGS. 1 and 2, thesupernatant liquid from the phase separation tank 150, the filtrate fromactive filter 160, and/or the filtrate from ultraclarification unit 180may be collected, stored in gray water tank 170 or lagoon 175, andrecycled. This filtrate water may be utilized as dilution water for theprocess or recirculated into the process at the rate required to achieveoptimum chemical performance of the reagents A, B, and (optionally) C.This recirculation rate varies based upon the nature and concentrationof the manure slurry.

The filtrate is also suitable for irrigation, fertilization and landspreading. The limiting nutrient remaining in the filtrate from theprocess for such use is typically the solubilized potash constituent andin some cases the nitrogen constituent. Typically this filtrate isacceptable for land application at five to ten times the normalapplication rate of raw manure, digested manure, or the filtrate fromthe mechanical separation of either. In many regions the increasedapplication rate is due to the elimination of phosphorous as thelimiting nutrient by the applicant's process; effluents containingphosphorous are typically subject to more stringent spreadinglimitations.

The nutrient, suspended solids and bacteria contaminant levels of thefiltrate from the applicant's process disclosed herein are sufficientlylow to allow for cost effective sterilization of this filtrate withcommercial ozone treatment equipment. To the best of the applicant'sknowledge, these low contaminant levels have not been previouslyachieved in a commercial manure treatment process, at least on acommercially economical basis.

The dewatered manure captured in the active filtration separationequipment contains organic nitrogen nutrient levels equivalent to aliquid manure mass two to three times larger. In addition, conventionalmanure dewatering systems capture the larger particulate matter andallow for passage of the finer organic matter into the filtrate, thusrendering the filtrate unsuitable for the above described uses. Inaddition, the land application of the liquid manure filtrate from theconventional manure dewatering, separation systems allow for the releaseof the inherent fine particulate as problematic sediment and nutrientsto the proximate waterways. The applicant's process sequesters thesignificant majority if not all of the fine particulate as well as thephosphorous compounds and a significant portion of the organic nitrogencompounds with the solid phase dewatered manure mass which is landapplied as a solid. This mitigates the release of the fine particulatematter and nutrients common to distribution of these materials in theconventional manure separator filtrate.

This characteristic of the dewatered manure solids is of particularbenefit to centralized manure composting or digestion facilities.Conventional technologies allow for the transport of either all of theliquid manure as a slurry or only the dewatered manure solids from thedistributed farms to the central processing site. The processing of allof the liquid manure as a slurry is generally not cost effective as thetransportation cost and the system infrastructure requirements for suchfacilities have been shown to be cost prohibitive. The processing ofonly the dewatered manure provides for only treating approximately 50%of the total manure solids from any given farm. In addition, asmentioned above, these mechanically separated solids consist of thelarger particulate and the finer organic matter is left at the farm inthe separated filtrate. This finer organic matter contains more of themore readily digestible materials in manure digesters than the largersolids captured in mechanical separators.

The applicant's process provides for transportation of all of thedigestible materials to the central site in approximately one third ofthe total volume of conventional liquid manure systems. In addition, itprovides for delivery of the more digestible materials typically leftbehind at the distributed farms. The more readily digestible materialsare understood to provide for higher yields of methane gas productionwithin the digester.

The compost produced directly from the dewatered manure from theapplicant's process or from digested manure utilizing the applicant'sprocess prior to or post-digester contains higher nutrient levels thanconventional compost due to the inherent retention of all of the solidsand nutrients in the dewatered mass, as opposed to losing half of themin the filtrate of conventional mechanically separated manure, which isthe source of the manure for conventional composting operations.

Additionally, the phosphorous compounds within the solid manure massfrom the applicant's process are rendered insoluble by their reactionwith the ferric chloride to produce ferric phosphate. While thischaracteristic depletes the value of the manure as a source of phosphatecompounds for fertilization of croplands, it is a considerable benefitin environmentally sensitive areas. Certain watershed areas throughoutthe United States have phosphate levels sufficiently high that theyseverely negatively impact the downstream watershed basin by virtue ofelevated levels of soluble phosphate. The ferric phosphate in the manuresolids from the applicant's process is substantially insoluble, andtherefore may become, at worst case, a portion of the insoluble sedimenton the bottom of the watersheds streams, rivers and bays. Givenappropriate regulatory approvals, farm operators may spread thesetreated manure solids on their phosphate overloaded lands in lieu ofhaving to ship their manure to distant locations to meet theenvironmental regulations.

Similarly, the filtrate from the process is essentially free of anyphosphate compounds and is significantly depleted of organic nitrogencompounds, as well as depleted of up to 50% of the dissolved ammoniacompounds. As with the manure solids this characteristic depletes thefertilization value of this material. However, in environmentallysensitive areas the disposition of the liquid fraction of the manure maybe a cost prohibitive expense to farmers. The nature of the filtratefrom this process will typically allow for its utilization as irrigationwater to the hydraulic limit of the lands proximate to the farm, whichis generally multiple times greater than would be allowed given thenutrient loading limitation resulting from the use of prior artprocesses. This provides a significant cost savings to the farmer, evenin light of the depleted fertilization value.

One additional significant benefit in the spreading of the filtrate fromthe applicant's process is the significant reduction of odor present inthe filtrate. The agricultural community is under constant scrutiny forcontrol of the odor of land applied manure. There are no methods knownto the applicant which achieve the level of odor reduction exhibited bythe applicant's process.

An Exemplary Design of an Apparatus of the Present Invention

The following description of aspects of one embodiment of theapplicant's manure waste treatment apparatus is meant only to beexemplary and not limiting.

Referring to FIG. 2, one embodiment of the applicant's manure wastetreatment apparatus was provided as follows:

Manure Source 102: A dairy operation producing about 30,000 gallons ofliquid manure waste per day, which was collected in a pit.

Pump 105: A Model 3P682 pump manufactured by the Dayton Company,delivering a flow rate of liquid manure waste of about 30 gallons perminute.

Phase Separation Tank 150: The optimum tank configuration appears to beabout 3.5 feet in diameter by about 10 feet high. The pitched, wideprofile agitator blades are set at least 24 inches above the bottom ofthe tank, near the middle three foot level and near the six to eightfoot level of the tank. The agitator speed varies with the nature of thesolids within the manure slurry; however 20 to 30 rpm appears to be anoptimum speed. The optimum flow rate for this configuration of tankappears to be in the range of 30 to 60 gallons per minute, and five toten minutes, and in certain cases up to 20 minutes, appears to be theoptimum residence time to achieve the separation of the clarifiedsupernatant liquid phase from the thickened flocculated solid slurryphase.Active Filter 160: A “Dry Box 15000” active filter manufactured and soldby Idee e Prodotti S.r.l. of Milan, Italy. Alternatively manufacturedand sold by Innovative environmental Products of Livonia, N.Y. underlicense to Idee e Prodotti. The DryBox is preferably of the improveddesign which includes the supplemental air supply system forsupplemental dewatering and the improved door seal configuration forsafe multiple uses of the filter cloths.Ultraclarification Unit 180: A “Squeeze Box” squeeze tower pressmanufactured and sold by Idee e Prodotti S.r.l. of Milan, Italy.Gray Water Tank 170: A 1000 gallon polypropylene tank, flat bottom witha top and a high side outlet and low side outlet plus an overflowfitting. The filtrate enters the tank and is pumped away as needed todownstream disposition. Periodically the tank level may be manuallyraised to allow flow out of the high side outlet in order to flush outany floating solids that have accumulated over time. The lower sideoutlet is a least 6 inches above the bottom of the tank in order toavoid removal of any sediment that may accumulate over time. Alternatelythe filtrate may be stored in a lagoon or the excess water from the graywater tank may be sent to a lagoon.

It is, therefore, apparent that there has been provided, in accordancewith the present invention, a method and apparatus for treating a liquidvolume containing animal waste. While this invention has been describedin conjunction with preferred embodiments thereof, it is evident thatmany alternatives, modifications, and variations will be apparent tothose skilled in the art. Accordingly, it is intended to embrace allsuch alternatives, modifications and variations that fall within thespirit and broad scope of the appended claims.

1. A method for treating a liquid containing waste manure, the methodcomprising: a. providing a treatment apparatus comprising at least afirst vessel, and a filtration system in liquid communication with thefirst vessel, the filtration system comprising a first active filterincluding a first housing, a first displaceable filter medium, and afirst displacement actuator disposed between the first housing and thefirst displaceable filter medium; b. delivering a portion of the liquidcontaining waste manure to the first vessel; c. adding a first reagentto the portion of liquid containing waste manure to cause the formationof waste manure flocs of a first size; d. adding a second reagent to theportion of liquid containing waste manure to cause growth of the wastemanure flocs of the first size into separable waste manure flocs; e.separating the portion of liquid containing separable waste manure flocswithin the filtration system into a waste manure sludge and a firstfiltrate; and f. dewatering the waste manure sludge by actuating saidfirst displacement actuator to displace said first displaceable filtermedium and producing a dewatered waste manure solid cake and a secondfiltrate wherein at least 85 weight percent of the organic nitrogen andat least about 97.5 weight percent of the phosphates and at least 94weight percent of the total manure solids that were present in theportion of the liquid containing waste manure delivered to the firstvessel is contained in the dewatered waste manure solid cake.
 2. Themethod as recited in claim 1, wherein the first reagent is ferricchloride, and the second reagent includes a cationic polymer.
 3. Themethod as recited in claim 2, further comprising adding a third reagentto the portion of liquid containing waste manure flocs to cause furthergrowth of the separable waste manure flocs.
 4. The method as recited inclaim 3, wherein the third reagent includes an anionic polymer.
 5. Themethod as recited in claim 1, wherein the first vessel is comprised ofan elongated pipe through which flows the portion of the liquidcontaining waste manure, and wherein the first reagent is continuouslyinjected into the elongated pipe.
 6. The method as recited in claim 1,wherein the first vessel is comprised of a tank, the portion of theliquid containing waste manure is delivered to the tank as a batch, andwherein the first reagent is delivered to the tank and mixed with theportion of the liquid containing waste manure.
 7. The method as recitedin claim 1, wherein dewatering the waste manure sludge is performed byfirst manipulating the sludge by repeating the cycle of actuating thefirst displacement actuator and releasing the first displacementactuator for at least two cycles.
 8. The method as recited in claim 1,wherein the filtration system is further comprised of a second filter influid communication with the first filter to receive the first andsecond filtrates, and the method further comprises further filtering thefirst and second filtrates with the second filter.
 9. The method asrecited in claim 8, wherein the second filter is comprised of a secondhousing, a second displaceable filter medium, and at least a seconddisplacement actuator disposed between the second housing and the seconddisplaceable filter medium.
 10. The method as recited in claim 1,wherein separating the separable waste manure flocs within thefiltration system into a waste manure sludge and a first filtrate anddewatering the waste manure sludge to produce a waste manure solid and asecond filtrate is performed by delivering a first amount of the liquidcontaining separable waste manure flocs into the first filter,dewatering the sludge from the first amount of liquid by actuating thefirst displacement actuator, and then delivering a second amount of theliquid containing separable waste manure flocs into the first filter,and dewatering the sludge from the second amount of liquid by actuatingthe first displacement actuator.
 11. The method as recited in claim 1,further comprising handling the separable waste flocs at sufficientlylow shear rates to prevent size reduction of the separable waste flocs.12. The method as recited in claim 1, wherein the apparatus is furthercomprised of a phase separation tank, and wherein the method furthercomprises delivering the portion of liquid containing separable wastemanure flocs to the phase separation tank, and separating the portion ofliquid containing separable waste manure flocs into a stream ofsupernatant liquid and a stream of concentrated separable waste manureflocs.
 13. The method as recited in claim 1, wherein the liquidcontaining waste manure includes sand, and wherein the method comprisesremoving at least a portion of the sand from the liquid beforedelivering the portion of the liquid containing waste manure to thefirst vessel.
 14. The method as recited in claim 1, further comprisingcomposting the dewatered waste manure solid cake within the firsthousing of the first filter by causing air to flow through the solidcake.
 15. The method of claim 14, further comprising repeatedly cyclingthe first displacement actuator from an unactuated state to an actuatedstate during composting the dewatered waste manure solid cake.
 16. Themethod as recited in claim 14, further comprising adding an amendmentmaterial to the portion of liquid containing separable waste manureflocs prior to separating the portion of liquid containing separablewaste manure flocs within the filtration system into the waste manuresludge and the first filtrate, wherein the amendment material increasesthe porosity of the dewatered waste manure solid cake.
 17. The method asrecited in claim 1, further comprising adding an amendment material tothe portion of liquid containing separable waste manure flocs prior toseparating the portion of liquid containing separable waste manure flocswithin the filtration system into the waste manure sludge and the firstfiltrate, wherein the amendment material increases the porosity of thedewatered waste manure solid cake.
 18. The method of claim 1, whereinthe phosphates in the dewatered waste manure solid cake are waterinsoluble phosphates.
 19. The method of claim 1, wherein the organicnitrogen compounds in the dewatered waste manure solid cake are waterinsoluble organic nitrogen compounds.
 20. The method of claim 1, whereinat least 99% of fecal matter present in the portion of the liquidcontaining waste manure delivered to the first vessel is contained inthe dewatered waste manure solid.
 21. A method for treating a liquidcontaining waste manure, the method comprising: a. providing a treatmentapparatus comprising at least a first vessel, and a filtration system inliquid communication with the first vessel, the filtration systemcomprising a first active filter including a first housing, a firstdisplaceable filter medium, and a first displacement actuator disposedbetween the first housing and the first displaceable filter medium; b.delivering a portion of the liquid containing waste manure to the firstvessel; c. adding a first reagent to the portion of liquid containingwaste manure to cause the formation of waste manure flocs of a firstsize; d. adding a second reagent to the portion of liquid containingwaste manure to cause growth of the waste manure flocs of the first sizeinto separable waste manure flocs; e. separating the portion of liquidcontaining separable waste manure flocs within the filtration systeminto a waste manure sludge and a first filtrate; f. dewatering the wastemanure sludge by actuating said first displacement actuator to displacesaid first displaceable filter medium and producing a dewatered wastemanure solid cake and a second filtrate; and q. composting the dewateredwaste manure solid cake within the active filter by causing air to flowthrough the solid cake.
 22. The method of claim 21, further comprisingrepeatedly cycling the first displacement actuator from an unactuatedstate to an actuated state during composting the dewatered waste manuresolid cake.
 23. The method of claim 21, further comprising adding anamendment material to the portion of liquid containing separable wastemanure flocs prior to separating the portion of liquid containingseparable waste manure flocs within the filtration system into the wastemanure sludge and the first filtrate, wherein the amendment materialincreases the porosity of the dewatered waste manure solid cake.
 24. Themethod of claim 21, wherein at least 85 weight percent of the organicnitrogen and at least about 97.5 weight percent of the phosphates and atleast 94 weight percent of the total manure solids that were present inthe portion of the liquid containing waste manure delivered to the firstvessel is contained in the dewatered waste manure solid cake.
 25. Themethod of claim 21, wherein at least 99% of fecal matter that waspresent in the portion of the liquid containing waste manure deliveredto the first vessel is contained in the dewatered waste manure solidcake.
 26. A method for treating a liquid containing waste manure, themethod comprising: a. providing a treatment apparatus comprising atleast a first vessel, and a filtration system in liquid communicationwith the first vessel, the filtration system comprising a first activefilter including a first housing, a first displaceable filter medium,and a first displacement actuator disposed between the first housing andthe first displaceable filter medium; b. delivering a portion of theliquid containing waste manure to the first vessel; c. adding a firstreagent to the portion of liquid containing waste manure to cause theformation of waste manure flocs of a first size; d. adding a secondreagent to the portion of liquid containing waste manure to cause growthof the waste manure flocs of the first size into separable waste manureflocs; e. separating the portion of liquid containing separable wastemanure flocs within the filtration system into a waste manure sludge anda first filtrate; f. dewatering the waste manure sludge by actuatingsaid first displacement actuator to displace said first displaceablefilter medium and producing a dewatered waste manure solid and a secondfiltrate; and g. adding an amendment material to the portion of liquidcontaining separable waste manure flocs prior to separating the portionof liquid containing separable waste manure flocs within the filtrationsystem into the waste manure sludge and the first filtrate, wherein theamendment material increases the porosity of the dewatered waste manuresolid.